.\" 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 "" v3.2.2
+.TH MDADM 8 "" v3.2.5
.SH NAME
mdadm \- manage MD devices
.I aka
.I mdadm
will be silent unless there is something really important to report.
+.TP
+.BR \-\-offroot
+Set first character of argv[0] to @ to indicate mdadm was launched
+from initrd/initramfs and should not be shutdown by systemd as part of
+the regular shutdown process. This option is normally only used by
+the system's initscripts. Please see here for more details on how
+systemd handled argv[0]:
+.IP
+.B http://www.freedesktop.org/wiki/Software/systemd/RootStorageDaemons
+.PP
+
+
.TP
.BR \-f ", " \-\-force
Be more forceful about certain operations. See the various modes for
recovery operation can be checkpointed and restarted. The different
sub-versions store the superblock at different locations on the
device, either at the end (for 1.0), at the start (for 1.1) or 4K from
-the start (for 1.2). "1" is equivalent to "1.0".
+the start (for 1.2). "1" is equivalent to "1.2" (the commonly
+preferred 1.x format).
'if '{DEFAULT_METADATA}'1.2' "default" is equivalent to "1.2".
.IP ddf
Use the "Industry Standard" DDF (Disk Data Format) format defined by
by a digit string). See below under
.BR "Auto Assembly" .
+.TP
+.B \-\-prefer=
+When
+.I mdadm
+needs to print the name for a device it normally finds the name in
+.B /dev
+which refers to the device and is shortest. When a path component is
+given with
+.B \-\-prefer
+.I mdadm
+will prefer a longer name if it contains that component. For example
+.B \-\-prefer=by-uuid
+will prefer a name in a subdirectory of
+.B /dev
+called
+.BR by-uuid .
+
+This functionality is currently only provided by
+.B \-\-detail
+and
+.BR \-\-monitor .
+
.SH For create, build, or grow:
.TP
A suffix of 'M' or 'G' can be given to indicate Megabytes or
Gigabytes respectively.
+Sometimes a replacement drive can be a little smaller than the
+original drives though this should be minimised by IDEMA standards.
+Such a replacement drive will be rejected by
+.IR md .
+To guard against this it can be useful to set the initial size
+slightly smaller than the smaller device with the aim that it will
+still be larger than any replacement.
+
This value can be set with
.B \-\-grow
-for RAID level 1/4/5/6. If the array was created with a size smaller
-than the currently active drives, the extra space can be accessed
-using
+for RAID level 1/4/5/6 though
+.B CONTAINER
+based arrays such as those with IMSM metadata may not be able to
+support this.
+If the array was created with a size smaller than the currently
+active drives, the extra space can be accessed using
.BR \-\-grow .
The size can be given as
.B max
.B "\-\-grow \-\-size="
command.
-This value can not be used with
+This value cannot be used when creating a
.B CONTAINER
-metadata such as DDF and IMSM.
+such as with DDF and IMSM metadata, though it perfectly valid when
+creating an array inside a container.
.TP
.BR \-Z ", " \-\-array\-size=
The file must be stored on a separate device, not on the RAID array
being reshaped.
+.TP
+.BR \-\-continue
+This option is complementary to the
+.B \-\-freeze-reshape
+option for assembly. It is needed when
+.B \-\-grow
+operation is interrupted and it is not restarted automatically due to
+.B \-\-freeze-reshape
+usage during array assembly. This option is used together with
+.BR \-G
+, (
+.BR \-\-grow
+) command and device for a pending reshape to be continued.
+All parameters required for reshape continuation will be read from array metadata.
+If initial
+.BR \-\-grow
+command had required
+.BR \-\-backup\-file=
+option to be set, continuation option will require to have exactly the same
+backup file given as well.
+.IP
+Any other parameter passed together with
+.BR \-\-continue
+option will be ignored.
+
.TP
.BR \-N ", " \-\-name=
Set a
.I mdadm
will not try to be so clever.
+.TP
+.BR \-o ", " \-\-readonly
+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.
+
.TP
.BR \-a ", " "\-\-auto{=yes,md,mdp,part,p}{NN}"
Instruct mdadm how to create the device file if needed, possibly allocating
non-standard name. Names that are not in 'standard' format are only
allowed in "/dev/md/".
+This is meaningful with
+.B \-\-create
+or
+.BR \-\-build .
+
.ig XX
.\".TP
.\".BR \-\-symlink = no
.\"
.XX
+.TP
+.BR \-a ", " "\-\-add"
+This option can be used in Grow mode in two cases.
+
+If the target array is a Linear array, then
+.B \-\-add
+can be used to add one or more devices to the array. They
+are simply catenated on to the end of the array. Once added, the
+devices cannot be removed.
+
+If the
+.B \-\-raid\-disks
+option is being used to increase the number of devices in an array,
+then
+.B \-\-add
+can be used to add some extra devices to be included in the array.
+In most cases this is not needed as the extra devices can be added as
+spares first, and then the number of raid-disks can be changed.
+However for RAID0, it is not possible to add spares. So to increase
+the number of devices in a RAID0, it is necessary to set the new
+number of devices, and to add the new devices, in the same command.
+
.SH For assemble:
.TP
.BR \-a ", " "\-\-auto{=no,yes,md,mdp,part}"
See this option under Create and Build options.
-.TP
-.BR \-a ", " "\-\-add"
-This option can be used in Grow mode in two cases.
-
-If the target array is a Linear array, then
-.B \-\-add
-can be used to add one or more devices to the array. They
-are simply catenated on to the end of the array. Once added, the
-devices cannot be removed.
-
-If the
-.B \-\-raid\-disks
-option is being used to increase the number of devices in an array,
-then
-.B \-\-add
-can be used to add some extra devices to be included in the array.
-In most cases this is not needed as the extra devices can be added as
-spares first, and then the number of raid-disks can be changed.
-However for RAID0, it is not possible to add spares. So to increase
-the number of devices in a RAID0, it is necessary to set the new
-number of devices, and to add the new devices, in the same command.
-
.TP
.BR \-b ", " \-\-bitmap=
Specify the bitmap file that was given when the array was created. If
corrupt in some way so that assembling the array normally fails. It
will cause any internal bitmap to be ignored.
+.TP
+.BR \-\-freeze\-reshape
+Option is intended to be used in start-up scripts during initrd boot phase.
+When array under reshape is assembled during initrd phase, this option
+stops reshape after reshape critical section is being restored. This happens
+before file system pivot operation and avoids loss of file system context.
+Losing file system context would cause reshape to be broken.
+
+Reshape can be continued later using the
+.B \-\-continue
+option for the grow command.
+
.SH For Manage mode:
.TP
.BR \-a ", " \-\-add
hot-add listed devices.
If a device appears to have recently been part of the array
-(possibly it failed or was removed) the device is re\-added as describe
+(possibly it failed or was removed) the device is re\-added as described
in the next point.
If that fails or the device was never part of the array, the device is
added as a hot-spare.
.TP
.BR \-\-rebuild\-map ", " \-r
Rebuild the map file
-.RB ( /var/run/mdadm/map )
+.RB ( {MAP_PATH} )
that
.I mdadm
uses to help track which arrays are currently being assembled.
In the second usage example, all devices listed are treated as md
devices and assembly is attempted.
In the third (where no devices are listed) all md devices that are
-listed in the configuration file are assembled. If not arrays are
+listed in the configuration file are assembled. If no arrays are
described by the configuration file, then any arrays that
can be found on unused devices will be assembled.
but leaves that to
.IR udev .
It does record information in
-.B /var/run/mdadm/map
+.B {MAP_PATH}
which will allow
.I udev
to choose the correct name.
will first attempt to assemble all the arrays listed in the config
file.
-In no array at listed in the config (other than those marked
+If no arrays are listed in the config (other than those marked
.BR <ignore> )
it will look through the available devices for possible arrays and
will try to assemble anything that it finds. Arrays which are tagged
.IP \(bu 4
increase or decrease the "raid\-devices" attribute of RAID0, RAID1, RAID4,
RAID5, and RAID6.
-.IP \bu 4
+.IP \(bu 4
change the chunk-size and layout of RAID0, RAID4, RAID5 and RAID6.
-.IP \bu 4
+.IP \(bu 4
convert between RAID1 and RAID5, between RAID5 and RAID6, between
-RAID0, RAID5, and RAID5, and between RAID0 and RAID10 (in the near-2 mode).
+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.
.PP
-Using GROW on containers is currently only support for Intel's IMSM
+Using GROW on containers is currently supported only for Intel's IMSM
container format. The number of devices in a container can be
increased - which affects all arrays in the container - or an array
in a container can be converted between levels where those levels are
supported by the container, and the conversion is on of those listed
-above.
+above. Resizing arrays in an IMSM container with
+.B "--grow --size"
+is not yet supported.
Grow functionality (e.g. expand a number of raid devices) for Intel's
IMSM container format has an experimental status. It is guarded by the
are synchronised.
Note that when an array changes size, any filesystem that may be
-stored in the array will not automatically grow for shrink to use or
+stored in the array will not automatically grow or shrink to use or
vacate the space. The
filesystem will need to be explicitly told to use the extra space
after growing, or to reduce its size
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 it complete a new bitmap can be created.
+can be changed. Once the change is complete a new bitmap can be created.
.SS RAID\-DEVICES CHANGES
line.
.IP +
-Does the device have a valid md superblock. If a specific metadata
-version is request with
+Does the device have a valid md superblock? If a specific metadata
+version is requested with
.B \-\-metadata
or
.B \-e
current host, the device will be rejected.
..
+.PP
.I mdadm
keeps a list of arrays that it has partially assembled in
-.B /var/run/mdadm/map
-(or
-.B /var/run/mdadm.map
-if the directory doesn't exist. Or maybe even
-.BR /dev/.mdadm.map ).
+.BR {MAP_PATH} .
If no array exists which matches
the metadata on the new device,
.I mdadm
.B /dev/md0
out of all such devices with a RAID superblock with a minor number of 0.
-.B " mdadm \-\-monitor \-\-scan \-\-daemonise > /var/run/mdadm"
+.B " mdadm \-\-monitor \-\-scan \-\-daemonise > /run/mdadm/mon.pid"
.br
If config file contains a mail address or alert program, run mdadm in
the background in monitor mode monitoring all md devices. Also write
pid of mdadm daemon to
-.BR /var/run/mdadm .
+.BR /run/mdadm/mon.pid .
.B " mdadm \-Iq /dev/somedevice"
.br
Any devices which are components of /dev/md4 will be marked as faulty
and then remove from the array.
-.B " mdadm --grow /dev/md4 --level=6 --backup-file=/root/backup-md4
+.B " mdadm --grow /dev/md4 --level=6 --backup-file=/root/backup-md4"
.br
The array
.B /dev/md4
.BR mdadm.conf (5)
for more details.
-.SS /var/run/mdadm/map
+.SS {MAP_PATH}
When
.B \-\-incremental
mode is used, this file gets a list of arrays currently being created.
-If
-.B /var/run/mdadm
-does not exist as a directory, then
-.B /var/run/mdadm.map
-is used instead. If
-.B /var/run
-is not available (as may be the case during early boot),
-.B /dev/.mdadm.map
-is used on the basis that
-.B /dev
-is usually available very early in boot.
.SH DEVICE NAMES
For further information on mdadm usage, MD and the various levels of
RAID, see:
.IP
-.B http://linux\-raid.osdl.org/
+.B http://raid.wiki.kernel.org/
.PP
(based upon Jakob \(/Ostergaard's Software\-RAID.HOWTO)
.\".PP
projects / thirdparty / mdadm.git / blobdiff