path: root/
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Diffstat (limited to '')
1 files changed, 117 insertions, 25 deletions
diff --git a/ b/
index f789d434..ea45bbc8 100644
--- a/
+++ b/
@@ -5,7 +5,7 @@
.\" the Free Software Foundation; either version 2 of the License, or
.\" (at your option) any later version.
.\" See file COPYING in distribution for details.
-.TH MDADM 8 "" v4.0
+.TH MDADM 8 "" v4.1-rc1
mdadm \- manage MD devices
.I aka
@@ -126,7 +126,7 @@ of component devices and changing the number of active devices in
Linear and RAID levels 0/1/4/5/6,
changing the RAID level between 0, 1, 5, and 6, and between 0 and 10,
changing the chunk size and layout for RAID 0,4,5,6,10 as well as adding or
-removing a write-intent bitmap.
+removing a write-intent bitmap and changing the array's consistency policy.
.B "Incremental Assembly"
@@ -267,13 +267,13 @@ the exact meaning of this option in different contexts.
.BR \-c ", " \-\-config=
Specify the config file or directory. Default is to use
-.B /etc/mdadm/mdadm.conf
+.B /etc/mdadm.conf
-.BR /etc/mdadm/mdadm.conf.d ,
+.BR /etc/mdadm.conf.d ,
or if those are missing then
-.B /etc/mdadm.conf
+.B /etc/mdadm/mdadm.conf
-.BR /etc/mdadm.conf.d .
+.BR /etc/mdadm/mdadm.conf.d .
If the config file given is
.B "partitions"
then nothing will be read, but
@@ -541,6 +541,8 @@ A value of
restores the apparent size of the array to be whatever the real
amount of available space is.
+Clustered arrays do not support this parameter yet.
.BR \-c ", " \-\-chunk=
Specify chunk size of kilobytes. The default when creating an
@@ -724,7 +726,9 @@ When creating an array on devices which are 100G or larger,
.I mdadm
automatically adds an internal bitmap as it will usually be
beneficial. This can be suppressed with
-.B "\-\-bitmap=none".
+.B "\-\-bitmap=none"
+or by selecting a different consistency policy with
+.BR \-\-consistency\-policy .
.BR \-\-bitmap\-chunk=
@@ -923,7 +927,8 @@ will not try to be so clever.
Start the array
.B read only
rather than read-write as normal. No writes will be allowed to the
-array, and no resync, recovery, or reshape will be started.
+array, and no resync, recovery, or reshape will be started. It works with
+Create, Assemble, Manage and Misc mode.
.BR \-a ", " "\-\-auto{=yes,md,mdp,part,p}{NN}"
@@ -1015,6 +1020,45 @@ simultaneously. If not specified, this defaults to 4.
Specify journal device for the RAID-4/5/6 array. The journal device
should be a SSD with reasonable lifetime.
+.BR \-\-symlinks
+Auto creation of symlinks in /dev to /dev/md, option --symlinks must
+be 'no' or 'yes' and work with --create and --build.
+.BR \-k ", " \-\-consistency\-policy=
+Specify how the array maintains consistency in case of unexpected shutdown.
+Only relevant for RAID levels with redundancy.
+Currently supported options are:
+.B resync
+Full resync is performed and all redundancy is regenerated when the array is
+started after unclean shutdown.
+.B bitmap
+Resync assisted by a write-intent bitmap. Implicitly selected when using
+.BR \-\-bitmap .
+.B journal
+For RAID levels 4/5/6, journal device is used to log transactions and replay
+after unclean shutdown. Implicitly selected when using
+.BR \-\-write\-journal .
+.B ppl
+For RAID5 only, Partial Parity Log is used to close the write hole and
+eliminate resync. PPL is stored in the metadata region of RAID member drives,
+no additional journal drive is needed.
+Can be used with \-\-grow to change the consistency policy of an active array
+in some cases. See CONSISTENCY POLICY CHANGES below.
.SH For assemble:
@@ -1139,6 +1183,8 @@ argument given to this flag can be one of
.BR no\-bitmap ,
.BR bbl ,
.BR no\-bbl ,
+.BR ppl ,
+.BR no\-ppl ,
.BR metadata ,
.BR super\-minor .
@@ -1218,7 +1264,8 @@ is correct.
.B byteorder
option allows arrays to be moved between machines with different
+byte-order, such as from a big-endian machine like a Sparc or some
+MIPS machines, to a little-endian x86_64 machine.
When assembling such an array for the first time after a move, giving
.B "\-\-update=byteorder"
will cause
@@ -1279,6 +1326,16 @@ option will cause any reservation of space for a bad block list to be
removed. If the bad block list contains entries, this will fail, as
removing the list could cause data corruption.
+.B ppl
+option will enable PPL for a RAID5 array and reserve space for PPL on each
+device. There must be enough free space between the data and superblock and a
+write-intent bitmap or journal must not be used.
+.B no\-ppl
+option will disable PPL in the superblock.
.BR \-\-freeze\-reshape
Option is intended to be used in start-up scripts during initrd boot phase.
@@ -1291,6 +1348,10 @@ Reshape can be continued later using the
.B \-\-continue
option for the grow command.
+.BR \-\-symlinks
+See this option under Create and Build options.
.SH For Manage mode:
@@ -1465,9 +1526,8 @@ the device is found or <slot>:missing in case the device is not found.
.BR \-\-add-journal
-Recreate journal for RAID-4/5/6 array that lost a journal device. In the
-current implementation, this command cannot add a journal to an array
-that had a failed journal. To avoid interrupting on-going write opertions,
+Add journal to an existing array, or recreate journal for RAID-4/5/6 array
+that lost a journal device. To avoid interrupting on-going write opertions,
.B \-\-add-journal
only works for array in Read-Only state.
@@ -1631,6 +1691,10 @@ overwritten with zeros. With
the block where the superblock would be is overwritten even if it
doesn't appear to be valid.
+.B Note:
+Be careful to call \-\-zero\-superblock with clustered raid, make sure
+array isn't used or assembled in other cluster node before execute it.
.B \-\-kill\-subarray=
If the device is a container and the argument to \-\-kill\-subarray
@@ -1888,9 +1952,9 @@ The config file is only used if explicitly named with
or requested with (a possibly implicit)
.BR \-\-scan .
In the later case,
-.B /etc/mdadm/mdadm.conf
.B /etc/mdadm.conf
+.B /etc/mdadm/mdadm.conf
is used.
@@ -2144,12 +2208,14 @@ in the array exceed 100G is size, an internal write-intent bitmap
will automatically be added unless some other option is explicitly
requested with the
.B \-\-bitmap
-option. In any case space for a bitmap will be reserved so that one
-can be added layer with
+option or a different consistency policy is selected with the
+.B \-\-consistency\-policy
+option. In any case space for a bitmap will be reserved so that one
+can be added later with
.BR "\-\-grow \-\-bitmap=internal" .
-If the metadata type supports it (currently only 1.x metadata), space
-will be allocated to store a bad block list. This allows a modest
+If the metadata type supports it (currently only 1.x and IMSM metadata),
+space will be allocated to store a bad block list. This allows a modest
number of bad blocks to be recorded, allowing the drive to remain in
service while only partially functional.
@@ -2173,7 +2239,7 @@ be in use.
.B \-\-readonly
-start the array readonly \(em not supported yet.
+start the array in readonly mode.
.HP 12
@@ -2284,9 +2350,11 @@ superblock field in the subarray. Similar to updating an array in
.B \-U
.B \-\-update=
-option. Currently only
-.B name
-is supported.
+option. The supported options are
+.BR name ,
+.B ppl
+.BR no\-ppl .
.B name
@@ -2297,6 +2365,13 @@ re\-assembled. If updating
would change the UUID of an active subarray this operation is blocked,
and the command will end in an error.
+.B ppl
+.B no\-ppl
+options enable and disable PPL in the metadata. Currently supported only for
+IMSM subarrays.
.B \-\-examine
The device should be a component of an md array.
@@ -2630,6 +2705,8 @@ RAID0, RAID4, and RAID5, and between RAID0 and RAID10 (in the near-2 mode).
.IP \(bu 4
add a write-intent bitmap to any array which supports these bitmaps, or
remove a write-intent bitmap from such an array.
+.IP \(bu 4
+change the array's consistency policy.
Using GROW on containers is currently supported only for Intel's IMSM
@@ -2685,6 +2762,11 @@ Also the size of an array cannot be changed while it has an active
bitmap. If an array has a bitmap, it must be removed before the size
can be changed. Once the change is complete a new bitmap can be created.
+.B "--grow --size"
+is not yet supported for external file bitmap.
A RAID1 array can work with any number of devices from 1 upwards
@@ -2786,6 +2868,16 @@ can be added. Note that if you add a bitmap stored in a file which is
in a filesystem that is on the RAID array being affected, the system
will deadlock. The bitmap must be on a separate filesystem.
+The consistency policy of an active array can be changed by using the
+.B \-\-consistency\-policy
+option in Grow mode. Currently this works only for the
+.B ppl
+.B resync
+policies and allows to enable or disable the RAID5 Partial Parity Log (PPL).
.HP 12
@@ -2864,7 +2956,7 @@ This is the only context where the aliases are used. They are
usually provided by a
.I udev
rules mentioning
+.BR $env{DEVLINKS} .
.IP +
Does the device have a valid md superblock? If a specific metadata
@@ -3184,7 +3276,7 @@ uses this to find arrays when
is given in Misc mode, and to monitor array reconstruction
on Monitor mode.
-.SS /etc/mdadm/mdadm.conf (or /etc/mdadm.conf)
+.SS /etc/mdadm.conf
The config file lists which devices may be scanned to see if
they contain MD super block, and gives identifying information
@@ -3192,7 +3284,7 @@ they contain MD super block, and gives identifying information
.BR mdadm.conf (5)
for more details.
-.SS /etc/mdadm/mdadm.conf.d (or /etc/mdadm.conf.d)
+.SS /etc/mdadm.conf.d
A directory containing configuration files which are read in lexical