-Q, --query
Examine a device to see (1) if it is an md device and (2)
if it is a component of an md array. Information about
what is discovered is presented.
-D, --detail
Print details of one or more md devices.
--detail-platform
Print details of the platform's RAID capabilities
(firmware / hardware topology) for a given metadata
format. If used without argument, mdadm will scan all
controllers looking for their capabilities. Otherwise,
mdadm will only look at the controller specified by the
argument in form of an absolute filepath or a link, e.g.
/sys/devices/pci0000:00/0000:00:1f.2.
-Y, --export
When used with --detail, --detail-platform, --examine, or
--incremental output will be formatted as key=value pairs
for easy import into the environment.
With --incremental The value MD_STARTED indicates whether
an array was started (yes) or not, which may include a
reason (unsafe, nothing, no). Also the value MD_FOREIGN
indicates if the array is expected on this host (no), or
seems to be from elsewhere (yes).
-E, --examine
Print contents of the metadata stored on the named
device(s). Note the contrast between --examine and
--detail. --examine applies to devices which are
components of an array, while --detail applies to a whole
array which is currently active.
--sparc2.2
If an array was created on a SPARC machine with a 2.2
Linux kernel patched with RAID support, the superblock
will have been created incorrectly, or at least
incompatibly with 2.4 and later kernels. Using the
--sparc2.2 flag with --examine will fix the superblock
before displaying it. If this appears to do the right
thing, then the array can be successfully assembled using
--assemble --update=sparc2.2.
-X, --examine-bitmap
Report information about a bitmap file. The argument is
either an external bitmap file or an array component in
case of an internal bitmap. Note that running this on an
array device (e.g. /dev/md0) does not report the bitmap
for that array.
--examine-badblocks
List the bad-blocks recorded for the device, if a bad-
blocks list has been configured. Currently only 1.x and
IMSM metadata support bad-blocks lists.
--dump=directory
--restore=directory
Save metadata from lists devices, or restore metadata to
listed devices.
-R, --run
start a partially assembled array. If --assemble did not
find enough devices to fully start the array, it might
leaving it partially assembled. If you wish, you can then
use --run to start the array in degraded mode.
-S, --stop
deactivate array, releasing all resources.
-o, --readonly
mark array as readonly.
-w, --readwrite
mark array as readwrite.
--zero-superblock
If the device contains a valid md superblock, the block is
overwritten with zeros. With --force the block where the
superblock would be is overwritten even if it doesn't
appear to be valid.
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.
--kill-subarray=
If the device is a container and the argument to
--kill-subarray specifies an inactive subarray in the
container, then the subarray is deleted. Deleting all
subarrays will leave an 'empty-container' or spare
superblock on the drives. See --zero-superblock for
completely removing a superblock. Note that some formats
depend on the subarray index for generating a UUID, this
command will fail if it would change the UUID of an active
subarray.
--update-subarray=
If the device is a container and the argument to
--update-subarray specifies a subarray in the container,
then attempt to update the given superblock field in the
subarray. See below in MISC MODE for details.
-t, --test
When used with --detail, the exit status of mdadm is set
to reflect the status of the device. See below in MISC
MODE for details.
-W, --wait
For each md device given, wait for any resync, recovery,
or reshape activity to finish before returning. mdadm
will return with success if it actually waited for every
device listed, otherwise it will return failure.
--wait-clean
For each md device given, or each device in /proc/mdstat
if --scan is given, arrange for the array to be marked
clean as soon as possible. mdadm will return with success
if the array uses external metadata and we successfully
waited. For native arrays this returns immediately as the
kernel handles dirty-clean transitions at shutdown. No
action is taken if safe-mode handling is disabled.
--action=
Set the "sync_action" for all md devices given to one of
idle, frozen, check, repair. Setting to idle will abort
any currently running action though some actions will
automatically restart. Setting to frozen will abort any
current action and ensure no other action starts
automatically.
Details of check and repair can be found it md(4) under
SCRUBBING AND MISMATCHES.
