^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) RAID arrays
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) ===========
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4) Boot time assembly of RAID arrays
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) ---------------------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) Tools that manage md devices can be found at
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) https://www.kernel.org/pub/linux/utils/raid/
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) You can boot with your md device with the following kernel command
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) lines:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) for old raid arrays without persistent superblocks::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) md=<md device no.>,<raid level>,<chunk size factor>,<fault level>,dev0,dev1,...,devn
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) for raid arrays with persistent superblocks::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) md=<md device no.>,dev0,dev1,...,devn
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) or, to assemble a partitionable array::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) md=d<md device no.>,dev0,dev1,...,devn
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) ``md device no.``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) +++++++++++++++++
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) The number of the md device
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) ================= =========
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) ``md device no.`` device
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) ================= =========
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) 0 md0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) 1 md1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) 2 md2
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) 3 md3
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) 4 md4
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) ================= =========
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) ``raid level``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) ++++++++++++++
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) level of the RAID array
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) =============== =============
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) ``raid level`` level
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) =============== =============
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) -1 linear mode
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) 0 striped mode
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) =============== =============
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) other modes are only supported with persistent super blocks
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) ``chunk size factor``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) +++++++++++++++++++++
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) (raid-0 and raid-1 only)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) Set the chunk size as 4k << n.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) ``fault level``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) +++++++++++++++
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) Totally ignored
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) ``dev0`` to ``devn``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) ++++++++++++++++++++
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) e.g. ``/dev/hda1``, ``/dev/hdc1``, ``/dev/sda1``, ``/dev/sdb1``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) A possible loadlin line (Harald Hoyer <HarryH@Royal.Net>) looks like this::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) e:\loadlin\loadlin e:\zimage root=/dev/md0 md=0,0,4,0,/dev/hdb2,/dev/hdc3 ro
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) Boot time autodetection of RAID arrays
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) --------------------------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) When md is compiled into the kernel (not as module), partitions of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) type 0xfd are scanned and automatically assembled into RAID arrays.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) This autodetection may be suppressed with the kernel parameter
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) ``raid=noautodetect``. As of kernel 2.6.9, only drives with a type 0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) superblock can be autodetected and run at boot time.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) The kernel parameter ``raid=partitionable`` (or ``raid=part``) means
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) that all auto-detected arrays are assembled as partitionable.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89) Boot time assembly of degraded/dirty arrays
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) -------------------------------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92) If a raid5 or raid6 array is both dirty and degraded, it could have
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) undetectable data corruption. This is because the fact that it is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94) ``dirty`` means that the parity cannot be trusted, and the fact that it
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) is degraded means that some datablocks are missing and cannot reliably
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) be reconstructed (due to no parity).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98) For this reason, md will normally refuse to start such an array. This
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) requires the sysadmin to take action to explicitly start the array
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) despite possible corruption. This is normally done with::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) mdadm --assemble --force ....
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) This option is not really available if the array has the root
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) filesystem on it. In order to support this booting from such an
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) array, md supports a module parameter ``start_dirty_degraded`` which,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) when set to 1, bypassed the checks and will allows dirty degraded
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) arrays to be started.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) So, to boot with a root filesystem of a dirty degraded raid 5 or 6, use::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) md-mod.start_dirty_degraded=1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) Superblock formats
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) ------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) The md driver can support a variety of different superblock formats.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) Currently, it supports superblock formats ``0.90.0`` and the ``md-1`` format
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) introduced in the 2.5 development series.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) The kernel will autodetect which format superblock is being used.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) Superblock format ``0`` is treated differently to others for legacy
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) reasons - it is the original superblock format.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) General Rules - apply for all superblock formats
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) ------------------------------------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) An array is ``created`` by writing appropriate superblocks to all
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) devices.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) It is ``assembled`` by associating each of these devices with an
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) particular md virtual device. Once it is completely assembled, it can
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) be accessed.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) An array should be created by a user-space tool. This will write
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) superblocks to all devices. It will usually mark the array as
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) ``unclean``, or with some devices missing so that the kernel md driver
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) can create appropriate redundancy (copying in raid 1, parity
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) calculation in raid 4/5).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) When an array is assembled, it is first initialized with the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) SET_ARRAY_INFO ioctl. This contains, in particular, a major and minor
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) version number. The major version number selects which superblock
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) format is to be used. The minor number might be used to tune handling
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) of the format, such as suggesting where on each device to look for the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) superblock.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) Then each device is added using the ADD_NEW_DISK ioctl. This
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) provides, in particular, a major and minor number identifying the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) device to add.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) The array is started with the RUN_ARRAY ioctl.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) Once started, new devices can be added. They should have an
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) appropriate superblock written to them, and then be passed in with
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) ADD_NEW_DISK.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) Devices that have failed or are not yet active can be detached from an
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) array using HOT_REMOVE_DISK.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) Specific Rules that apply to format-0 super block arrays, and arrays with no superblock (non-persistent)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) --------------------------------------------------------------------------------------------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) An array can be ``created`` by describing the array (level, chunksize
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) etc) in a SET_ARRAY_INFO ioctl. This must have ``major_version==0`` and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) ``raid_disks != 0``.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) Then uninitialized devices can be added with ADD_NEW_DISK. The
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) structure passed to ADD_NEW_DISK must specify the state of the device
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) and its role in the array.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) Once started with RUN_ARRAY, uninitialized spares can be added with
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) HOT_ADD_DISK.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) MD devices in sysfs
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) -------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) md devices appear in sysfs (``/sys``) as regular block devices,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) e.g.::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) /sys/block/md0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) Each ``md`` device will contain a subdirectory called ``md`` which
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) contains further md-specific information about the device.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) All md devices contain:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) level
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) a text file indicating the ``raid level``. e.g. raid0, raid1,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) raid5, linear, multipath, faulty.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) If no raid level has been set yet (array is still being
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) assembled), the value will reflect whatever has been written
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) to it, which may be a name like the above, or may be a number
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199) such as ``0``, ``5``, etc.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) raid_disks
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202) a text file with a simple number indicating the number of devices
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) in a fully functional array. If this is not yet known, the file
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) will be empty. If an array is being resized this will contain
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) the new number of devices.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206) Some raid levels allow this value to be set while the array is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) active. This will reconfigure the array. Otherwise it can only
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208) be set while assembling an array.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209) A change to this attribute will not be permitted if it would
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210) reduce the size of the array. To reduce the number of drives
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211) in an e.g. raid5, the array size must first be reduced by
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212) setting the ``array_size`` attribute.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) chunk_size
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) This is the size in bytes for ``chunks`` and is only relevant to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216) raid levels that involve striping (0,4,5,6,10). The address space
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217) of the array is conceptually divided into chunks and consecutive
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218) chunks are striped onto neighbouring devices.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219) The size should be at least PAGE_SIZE (4k) and should be a power
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220) of 2. This can only be set while assembling an array
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222) layout
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) The ``layout`` for the array for the particular level. This is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) simply a number that is interpretted differently by different
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) levels. It can be written while assembling an array.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) array_size
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 228) This can be used to artificially constrain the available space in
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 229) the array to be less than is actually available on the combined
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 230) devices. Writing a number (in Kilobytes) which is less than
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 231) the available size will set the size. Any reconfiguration of the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 232) array (e.g. adding devices) will not cause the size to change.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 233) Writing the word ``default`` will cause the effective size of the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 234) array to be whatever size is actually available based on
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 235) ``level``, ``chunk_size`` and ``component_size``.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 236)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 237) This can be used to reduce the size of the array before reducing
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 238) the number of devices in a raid4/5/6, or to support external
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 239) metadata formats which mandate such clipping.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 240)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 241) reshape_position
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 242) This is either ``none`` or a sector number within the devices of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 243) the array where ``reshape`` is up to. If this is set, the three
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 244) attributes mentioned above (raid_disks, chunk_size, layout) can
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 245) potentially have 2 values, an old and a new value. If these
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 246) values differ, reading the attribute returns::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 247)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 248) new (old)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 249)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 250) and writing will effect the ``new`` value, leaving the ``old``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 251) unchanged.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 252)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 253) component_size
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 254) For arrays with data redundancy (i.e. not raid0, linear, faulty,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 255) multipath), all components must be the same size - or at least
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 256) there must a size that they all provide space for. This is a key
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 257) part or the geometry of the array. It is measured in sectors
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 258) and can be read from here. Writing to this value may resize
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 259) the array if the personality supports it (raid1, raid5, raid6),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 260) and if the component drives are large enough.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 261)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 262) metadata_version
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 263) This indicates the format that is being used to record metadata
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 264) about the array. It can be 0.90 (traditional format), 1.0, 1.1,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 265) 1.2 (newer format in varying locations) or ``none`` indicating that
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 266) the kernel isn't managing metadata at all.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 267) Alternately it can be ``external:`` followed by a string which
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 268) is set by user-space. This indicates that metadata is managed
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 269) by a user-space program. Any device failure or other event that
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 270) requires a metadata update will cause array activity to be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 271) suspended until the event is acknowledged.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 272)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 273) resync_start
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 274) The point at which resync should start. If no resync is needed,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 275) this will be a very large number (or ``none`` since 2.6.30-rc1). At
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 276) array creation it will default to 0, though starting the array as
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 277) ``clean`` will set it much larger.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 278)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 279) new_dev
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 280) This file can be written but not read. The value written should
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 281) be a block device number as major:minor. e.g. 8:0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 282) This will cause that device to be attached to the array, if it is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 283) available. It will then appear at md/dev-XXX (depending on the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 284) name of the device) and further configuration is then possible.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 285)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 286) safe_mode_delay
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 287) When an md array has seen no write requests for a certain period
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 288) of time, it will be marked as ``clean``. When another write
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 289) request arrives, the array is marked as ``dirty`` before the write
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 290) commences. This is known as ``safe_mode``.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 291) The ``certain period`` is controlled by this file which stores the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 292) period as a number of seconds. The default is 200msec (0.200).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 293) Writing a value of 0 disables safemode.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 294)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 295) array_state
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 296) This file contains a single word which describes the current
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 297) state of the array. In many cases, the state can be set by
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 298) writing the word for the desired state, however some states
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 299) cannot be explicitly set, and some transitions are not allowed.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 300)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 301) Select/poll works on this file. All changes except between
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 302) Active_idle and active (which can be frequent and are not
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 303) very interesting) are notified. active->active_idle is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 304) reported if the metadata is externally managed.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 305)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 306) clear
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 307) No devices, no size, no level
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 308)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 309) Writing is equivalent to STOP_ARRAY ioctl
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 310)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 311) inactive
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 312) May have some settings, but array is not active
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 313) all IO results in error
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 314)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 315) When written, doesn't tear down array, but just stops it
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 316)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 317) suspended (not supported yet)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 318) All IO requests will block. The array can be reconfigured.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 319)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 320) Writing this, if accepted, will block until array is quiessent
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 321)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 322) readonly
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 323) no resync can happen. no superblocks get written.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 324)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 325) Write requests fail
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 326)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 327) read-auto
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 328) like readonly, but behaves like ``clean`` on a write request.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 329)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 330) clean
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 331) no pending writes, but otherwise active.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 332)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 333) When written to inactive array, starts without resync
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 334)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 335) If a write request arrives then
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 336) if metadata is known, mark ``dirty`` and switch to ``active``.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 337) if not known, block and switch to write-pending
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 338)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 339) If written to an active array that has pending writes, then fails.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 340) active
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 341) fully active: IO and resync can be happening.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 342) When written to inactive array, starts with resync
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 343)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 344) write-pending
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 345) clean, but writes are blocked waiting for ``active`` to be written.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 346)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 347) active-idle
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 348) like active, but no writes have been seen for a while (safe_mode_delay).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 349)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 350) bitmap/location
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 351) This indicates where the write-intent bitmap for the array is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 352) stored.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 353)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 354) It can be one of ``none``, ``file`` or ``[+-]N``.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 355) ``file`` may later be extended to ``file:/file/name``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 356) ``[+-]N`` means that many sectors from the start of the metadata.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 357)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 358) This is replicated on all devices. For arrays with externally
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 359) managed metadata, the offset is from the beginning of the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 360) device.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 361)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 362) bitmap/chunksize
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 363) The size, in bytes, of the chunk which will be represented by a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 364) single bit. For RAID456, it is a portion of an individual
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 365) device. For RAID10, it is a portion of the array. For RAID1, it
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 366) is both (they come to the same thing).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 367)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 368) bitmap/time_base
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 369) The time, in seconds, between looking for bits in the bitmap to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 370) be cleared. In the current implementation, a bit will be cleared
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 371) between 2 and 3 times ``time_base`` after all the covered blocks
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 372) are known to be in-sync.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 373)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 374) bitmap/backlog
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 375) When write-mostly devices are active in a RAID1, write requests
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 376) to those devices proceed in the background - the filesystem (or
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 377) other user of the device) does not have to wait for them.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 378) ``backlog`` sets a limit on the number of concurrent background
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 379) writes. If there are more than this, new writes will by
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 380) synchronous.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 381)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 382) bitmap/metadata
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 383) This can be either ``internal`` or ``external``.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 384)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 385) ``internal``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 386) is the default and means the metadata for the bitmap
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 387) is stored in the first 256 bytes of the allocated space and is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 388) managed by the md module.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 389)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 390) ``external``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 391) means that bitmap metadata is managed externally to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 392) the kernel (i.e. by some userspace program)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 393)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 394) bitmap/can_clear
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 395) This is either ``true`` or ``false``. If ``true``, then bits in the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 396) bitmap will be cleared when the corresponding blocks are thought
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 397) to be in-sync. If ``false``, bits will never be cleared.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 398) This is automatically set to ``false`` if a write happens on a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 399) degraded array, or if the array becomes degraded during a write.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 400) When metadata is managed externally, it should be set to true
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 401) once the array becomes non-degraded, and this fact has been
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 402) recorded in the metadata.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 403)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 404) consistency_policy
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 405) This indicates how the array maintains consistency in case of unexpected
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 406) shutdown. It can be:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 407)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 408) none
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 409) Array has no redundancy information, e.g. raid0, linear.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 410)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 411) resync
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 412) Full resync is performed and all redundancy is regenerated when the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 413) array is started after unclean shutdown.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 414)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 415) bitmap
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 416) Resync assisted by a write-intent bitmap.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 417)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 418) journal
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 419) For raid4/5/6, journal device is used to log transactions and replay
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 420) after unclean shutdown.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 421)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 422) ppl
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 423) For raid5 only, Partial Parity Log is used to close the write hole and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 424) eliminate resync.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 425)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 426) The accepted values when writing to this file are ``ppl`` and ``resync``,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 427) used to enable and disable PPL.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 428)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 429) uuid
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 430) This indicates the UUID of the array in the following format:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 431) xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 432)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 433)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 434) As component devices are added to an md array, they appear in the ``md``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 435) directory as new directories named::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 436)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 437) dev-XXX
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 438)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 439) where ``XXX`` is a name that the kernel knows for the device, e.g. hdb1.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 440) Each directory contains:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 441)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 442) block
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 443) a symlink to the block device in /sys/block, e.g.::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 444)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 445) /sys/block/md0/md/dev-hdb1/block -> ../../../../block/hdb/hdb1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 446)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 447) super
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 448) A file containing an image of the superblock read from, or
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 449) written to, that device.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 450)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 451) state
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 452) A file recording the current state of the device in the array
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 453) which can be a comma separated list of:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 454)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 455) faulty
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 456) device has been kicked from active use due to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 457) a detected fault, or it has unacknowledged bad
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 458) blocks
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 459)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 460) in_sync
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 461) device is a fully in-sync member of the array
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 462)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 463) writemostly
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 464) device will only be subject to read
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 465) requests if there are no other options.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 466)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 467) This applies only to raid1 arrays.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 468)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 469) blocked
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 470) device has failed, and the failure hasn't been
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 471) acknowledged yet by the metadata handler.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 472)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 473) Writes that would write to this device if
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 474) it were not faulty are blocked.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 475)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 476) spare
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 477) device is working, but not a full member.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 478)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 479) This includes spares that are in the process
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 480) of being recovered to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 481)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 482) write_error
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 483) device has ever seen a write error.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 484)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 485) want_replacement
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 486) device is (mostly) working but probably
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 487) should be replaced, either due to errors or
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 488) due to user request.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 489)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 490) replacement
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 491) device is a replacement for another active
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 492) device with same raid_disk.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 493)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 494)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 495) This list may grow in future.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 496)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 497) This can be written to.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 498)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 499) Writing ``faulty`` simulates a failure on the device.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 500)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 501) Writing ``remove`` removes the device from the array.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 502)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 503) Writing ``writemostly`` sets the writemostly flag.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 504)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 505) Writing ``-writemostly`` clears the writemostly flag.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 506)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 507) Writing ``blocked`` sets the ``blocked`` flag.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 508)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 509) Writing ``-blocked`` clears the ``blocked`` flags and allows writes
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 510) to complete and possibly simulates an error.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 511)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 512) Writing ``in_sync`` sets the in_sync flag.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 513)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 514) Writing ``write_error`` sets writeerrorseen flag.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 515)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 516) Writing ``-write_error`` clears writeerrorseen flag.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 517)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 518) Writing ``want_replacement`` is allowed at any time except to a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 519) replacement device or a spare. It sets the flag.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 520)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 521) Writing ``-want_replacement`` is allowed at any time. It clears
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 522) the flag.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 523)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 524) Writing ``replacement`` or ``-replacement`` is only allowed before
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 525) starting the array. It sets or clears the flag.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 526)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 527)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 528) This file responds to select/poll. Any change to ``faulty``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 529) or ``blocked`` causes an event.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 530)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 531) errors
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 532) An approximate count of read errors that have been detected on
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 533) this device but have not caused the device to be evicted from
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 534) the array (either because they were corrected or because they
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 535) happened while the array was read-only). When using version-1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 536) metadata, this value persists across restarts of the array.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 537)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 538) This value can be written while assembling an array thus
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 539) providing an ongoing count for arrays with metadata managed by
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 540) userspace.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 541)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 542) slot
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 543) This gives the role that the device has in the array. It will
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 544) either be ``none`` if the device is not active in the array
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 545) (i.e. is a spare or has failed) or an integer less than the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 546) ``raid_disks`` number for the array indicating which position
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 547) it currently fills. This can only be set while assembling an
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 548) array. A device for which this is set is assumed to be working.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 549)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 550) offset
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 551) This gives the location in the device (in sectors from the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 552) start) where data from the array will be stored. Any part of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 553) the device before this offset is not touched, unless it is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 554) used for storing metadata (Formats 1.1 and 1.2).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 555)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 556) size
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 557) The amount of the device, after the offset, that can be used
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 558) for storage of data. This will normally be the same as the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 559) component_size. This can be written while assembling an
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 560) array. If a value less than the current component_size is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 561) written, it will be rejected.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 562)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 563) recovery_start
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 564) When the device is not ``in_sync``, this records the number of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 565) sectors from the start of the device which are known to be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 566) correct. This is normally zero, but during a recovery
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 567) operation it will steadily increase, and if the recovery is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 568) interrupted, restoring this value can cause recovery to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 569) avoid repeating the earlier blocks. With v1.x metadata, this
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 570) value is saved and restored automatically.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 571)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 572) This can be set whenever the device is not an active member of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 573) the array, either before the array is activated, or before
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 574) the ``slot`` is set.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 575)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 576) Setting this to ``none`` is equivalent to setting ``in_sync``.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 577) Setting to any other value also clears the ``in_sync`` flag.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 578)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 579) bad_blocks
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 580) This gives the list of all known bad blocks in the form of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 581) start address and length (in sectors respectively). If output
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 582) is too big to fit in a page, it will be truncated. Writing
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 583) ``sector length`` to this file adds new acknowledged (i.e.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 584) recorded to disk safely) bad blocks.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 585)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 586) unacknowledged_bad_blocks
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 587) This gives the list of known-but-not-yet-saved-to-disk bad
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 588) blocks in the same form of ``bad_blocks``. If output is too big
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 589) to fit in a page, it will be truncated. Writing to this file
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 590) adds bad blocks without acknowledging them. This is largely
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 591) for testing.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 592)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 593) ppl_sector, ppl_size
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 594) Location and size (in sectors) of the space used for Partial Parity Log
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 595) on this device.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 596)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 597)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 598) An active md device will also contain an entry for each active device
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 599) in the array. These are named::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 600)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 601) rdNN
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 602)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 603) where ``NN`` is the position in the array, starting from 0.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 604) So for a 3 drive array there will be rd0, rd1, rd2.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 605) These are symbolic links to the appropriate ``dev-XXX`` entry.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 606) Thus, for example::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 607)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 608) cat /sys/block/md*/md/rd*/state
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 609)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 610) will show ``in_sync`` on every line.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 611)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 612)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 613)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 614) Active md devices for levels that support data redundancy (1,4,5,6,10)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 615) also have
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 616)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 617) sync_action
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 618) a text file that can be used to monitor and control the rebuild
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 619) process. It contains one word which can be one of:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 620)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 621) resync
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 622) redundancy is being recalculated after unclean
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 623) shutdown or creation
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 624)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 625) recover
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 626) a hot spare is being built to replace a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 627) failed/missing device
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 628)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 629) idle
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 630) nothing is happening
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 631) check
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 632) A full check of redundancy was requested and is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 633) happening. This reads all blocks and checks
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 634) them. A repair may also happen for some raid
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 635) levels.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 636)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 637) repair
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 638) A full check and repair is happening. This is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 639) similar to ``resync``, but was requested by the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 640) user, and the write-intent bitmap is NOT used to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 641) optimise the process.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 642)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 643) This file is writable, and each of the strings that could be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 644) read are meaningful for writing.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 645)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 646) ``idle`` will stop an active resync/recovery etc. There is no
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 647) guarantee that another resync/recovery may not be automatically
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 648) started again, though some event will be needed to trigger
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 649) this.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 650)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 651) ``resync`` or ``recovery`` can be used to restart the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 652) corresponding operation if it was stopped with ``idle``.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 653)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 654) ``check`` and ``repair`` will start the appropriate process
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 655) providing the current state is ``idle``.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 656)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 657) This file responds to select/poll. Any important change in the value
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 658) triggers a poll event. Sometimes the value will briefly be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 659) ``recover`` if a recovery seems to be needed, but cannot be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 660) achieved. In that case, the transition to ``recover`` isn't
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 661) notified, but the transition away is.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 662)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 663) degraded
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 664) This contains a count of the number of devices by which the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 665) arrays is degraded. So an optimal array will show ``0``. A
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 666) single failed/missing drive will show ``1``, etc.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 667)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 668) This file responds to select/poll, any increase or decrease
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 669) in the count of missing devices will trigger an event.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 670)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 671) mismatch_count
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 672) When performing ``check`` and ``repair``, and possibly when
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 673) performing ``resync``, md will count the number of errors that are
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 674) found. The count in ``mismatch_cnt`` is the number of sectors
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 675) that were re-written, or (for ``check``) would have been
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 676) re-written. As most raid levels work in units of pages rather
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 677) than sectors, this may be larger than the number of actual errors
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 678) by a factor of the number of sectors in a page.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 679)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 680) bitmap_set_bits
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 681) If the array has a write-intent bitmap, then writing to this
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 682) attribute can set bits in the bitmap, indicating that a resync
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 683) would need to check the corresponding blocks. Either individual
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 684) numbers or start-end pairs can be written. Multiple numbers
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 685) can be separated by a space.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 686)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 687) Note that the numbers are ``bit`` numbers, not ``block`` numbers.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 688) They should be scaled by the bitmap_chunksize.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 689)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 690) sync_speed_min, sync_speed_max
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 691) This are similar to ``/proc/sys/dev/raid/speed_limit_{min,max}``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 692) however they only apply to the particular array.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 693)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 694) If no value has been written to these, or if the word ``system``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 695) is written, then the system-wide value is used. If a value,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 696) in kibibytes-per-second is written, then it is used.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 697)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 698) When the files are read, they show the currently active value
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 699) followed by ``(local)`` or ``(system)`` depending on whether it is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 700) a locally set or system-wide value.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 701)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 702) sync_completed
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 703) This shows the number of sectors that have been completed of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 704) whatever the current sync_action is, followed by the number of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 705) sectors in total that could need to be processed. The two
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 706) numbers are separated by a ``/`` thus effectively showing one
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 707) value, a fraction of the process that is complete.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 708)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 709) A ``select`` on this attribute will return when resync completes,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 710) when it reaches the current sync_max (below) and possibly at
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 711) other times.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 712)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 713) sync_speed
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 714) This shows the current actual speed, in K/sec, of the current
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 715) sync_action. It is averaged over the last 30 seconds.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 716)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 717) suspend_lo, suspend_hi
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 718) The two values, given as numbers of sectors, indicate a range
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 719) within the array where IO will be blocked. This is currently
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 720) only supported for raid4/5/6.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 721)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 722) sync_min, sync_max
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 723) The two values, given as numbers of sectors, indicate a range
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 724) within the array where ``check``/``repair`` will operate. Must be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 725) a multiple of chunk_size. When it reaches ``sync_max`` it will
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 726) pause, rather than complete.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 727) You can use ``select`` or ``poll`` on ``sync_completed`` to wait for
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 728) that number to reach sync_max. Then you can either increase
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 729) ``sync_max``, or can write ``idle`` to ``sync_action``.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 730)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 731) The value of ``max`` for ``sync_max`` effectively disables the limit.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 732) When a resync is active, the value can only ever be increased,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 733) never decreased.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 734) The value of ``0`` is the minimum for ``sync_min``.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 735)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 736)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 737)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 738) Each active md device may also have attributes specific to the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 739) personality module that manages it.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 740) These are specific to the implementation of the module and could
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 741) change substantially if the implementation changes.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 742)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 743) These currently include:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 744)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 745) stripe_cache_size (currently raid5 only)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 746) number of entries in the stripe cache. This is writable, but
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 747) there are upper and lower limits (32768, 17). Default is 256.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 748)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 749) strip_cache_active (currently raid5 only)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 750) number of active entries in the stripe cache
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 751)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 752) preread_bypass_threshold (currently raid5 only)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 753) number of times a stripe requiring preread will be bypassed by
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 754) a stripe that does not require preread. For fairness defaults
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 755) to 1. Setting this to 0 disables bypass accounting and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 756) requires preread stripes to wait until all full-width stripe-
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 757) writes are complete. Valid values are 0 to stripe_cache_size.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 758)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 759) journal_mode (currently raid5 only)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 760) The cache mode for raid5. raid5 could include an extra disk for
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 761) caching. The mode can be "write-throuth" and "write-back". The
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 762) default is "write-through".
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 763)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 764) ppl_write_hint
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 765) NVMe stream ID to be set for each PPL write request.
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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