.\" 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 "" v3.3.3
+.TH MDADM 8 "" v4.0
.SH NAME
mdadm \- manage MD devices
.I aka
.TP
.BR \-z ", " \-\-size=
-Amount (in Kibibytes) of space to use from each drive in RAID levels 1/4/5/6.
+Amount (in Kilobytes) of space to use from each drive in RAID levels 1/4/5/6.
This must be a multiple of the chunk size, and must leave about 128Kb
of space at the end of the drive for the RAID superblock.
If this is not specified
size, though if there is a variance among the drives of greater than 1%, a warning is
issued.
-A suffix of 'M' or 'G' can be given to indicate Megabytes or
+A suffix of 'K', 'M' or 'G' can be given to indicate Kilobytes, Megabytes or
Gigabytes respectively.
Sometimes a replacement drive can be a little smaller than the
.B "\-\-grow \-\-array\-size="
command.
-A suffix of 'M' or 'G' can be given to indicate Megabytes or
+A suffix of 'K', 'M' or 'G' can be given to indicate Kilobytes, Megabytes or
Gigabytes respectively.
A value of
.B max
.TP
.BR \-c ", " \-\-chunk=
-Specify chunk size of kibibytes. The default when creating an
+Specify chunk size of kilobytes. The default when creating an
array is 512KB. To ensure compatibility with earlier versions, the
default when building an array with no persistent metadata is 64KB.
This is only meaningful for RAID0, RAID4, RAID5, RAID6, and RAID10.
RAID4, RAID5, RAID6, and RAID10 require the chunk size to be a power
of 2. In any case it must be a multiple of 4KB.
-A suffix of 'M' or 'G' can be given to indicate Megabytes or
+A suffix of 'K', 'M' or 'G' can be given to indicate Kilobytes, Megabytes or
Gigabytes respectively.
.TP
bitmap, the chunksize defaults to 64Meg, or larger if necessary to
fit the bitmap into the available space.
-A suffix of 'M' or 'G' can be given to indicate Megabytes or
+A suffix of 'K', 'M' or 'G' can be given to indicate Kilobytes, Megabytes or
Gigabytes respectively.
.TP
.BR \-\-create ,
or
.B \-\-add
-command will be flagged as 'write-mostly'. This is valid for RAID1
+command will be flagged as 'write\-mostly'. This is valid for RAID1
only and means that the 'md' driver will avoid reading from these
devices if at all possible. This can be useful if mirroring over a
slow link.
mode, and write-behind is only attempted on drives marked as
.IR write-mostly .
+.TP
+.BR \-\-failfast
+subsequent devices listed in a
+.B \-\-create
+or
+.B \-\-add
+command will be flagged as 'failfast'. This is valid for RAID1 and
+RAID10 only. IO requests to these devices will be encouraged to fail
+quickly rather than cause long delays due to error handling. Also no
+attempt is made to repair a read error on these devices.
+
+If an array becomes degraded so that the 'failfast' device is the only
+usable device, the 'failfast' flag will then be ignored and extended
+delays will be preferred to complete failure.
+
+The 'failfast' flag is appropriate for storage arrays which have a
+low probability of true failure, but which may sometimes
+cause unacceptable delays due to internal maintenance functions.
+
.TP
.BR \-\-assume\-clean
Tell
which computed a different offset.
Setting the offset explicitly over-rides the default. The value given
-is in Kilobytes unless an 'M' or 'G' suffix is given.
+is in Kilobytes unless a suffix of 'K', 'M' or 'G' is used to explicitly
+indicate Kilobytes, Megabytes or Gigabytes respectively.
Since Linux 3.4,
.B \-\-data\-offset
the maximum number of nodes in the cluster that will use this device
simultaneously. If not specified, this defaults to 4.
+.TP
+.BR \-\-write-journal
+Specify journal device for the RAID-4/5/6 array. The journal device
+should be a SSD with reasonable lifetime.
+
+
.SH For assemble:
.TP
.B name
option will change the
.I name
-of the array as stored in the superblock and bitmap. This option only
-works for clustered environment.
+of the array as stored in the superblock. This is only supported for
+version-1 superblocks.
The
.B nodes
option will change the
.I nodes
-of the array as stored in the superblock. This is only supported for
-version-1 superblocks.
+of the array as stored in the bitmap superblock. This option only
+works for a clustered environment.
The
.B homehost
with \-\-cluster\-confirm. Valid arguments are <slot>:<devicename> in case
the device is found or <slot>:missing in case the device is not found.
+.TP
+.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,
+.B \-\-add-journal
+only works for array in Read-Only state.
+
+.TP
+.BR \-\-failfast
+Subsequent devices that are added or re\-added will have
+the 'failfast' flag set. This is only valid for RAID1 and RAID10 and
+means that the 'md' driver will avoid long timeouts on error handling
+where possible.
+.TP
+.BR \-\-nofailfast
+Subsequent devices that are re\-added will be re\-added without
+the 'failfast' flag set.
+
.P
Each of these options requires that the first device listed is the array
to be acted upon, and the remainder are component devices to be added,
projects / thirdparty / mdadm.git / blobdiff