system. As each device is detected,
.I mdadm
has a chance to include it in some array as appropriate.
+Optionally, when the
+.I \-\-fail
+flag is passed in we will remove the device from any active array
+instead of adding it.
If a
.B CONTAINER
.TP
.BR \-I ", " \-\-incremental
-Add a single device into an appropriate array, and possibly start the array.
+Add/remove a single device to/from an appropriate array, and possibly start the array.
.TP
.B \-\-auto-detect
.SH For Manage mode:
+.TP
+.BR \-t ", " \-\-test
+Unless a more serious error occurred,
+.I mdadm
+will exit with a status of 2 if no changes were made to the array and
+0 if at least one change was made.
+This can be useful when an indirect specifier such as
+.BR missing ,
+.B detached
+or
+.B faulty
+is used in requesting an operation on the array.
+.B \-\-test
+will report failure if these specifiers didn't find any match.
+
.TP
.BR \-a ", " \-\-add
-hot-add listed devices. For arrays with redundancy, the listed
-devices become available as spares. If the array is degraded, it will
-immediately start recovering data on to one of these spares.
+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
+in the next point.
+If that fails or the device was never part of the array, the device is
+added as a hot-spare.
+If the array is degraded, it will immediately start to rebuild data
+onto that spare.
+
+Note that this and the following options are only meaningful on array
+with redundancy. They don't apply to RAID0 or Linear.
.TP
.BR \-\-re\-add
-re-add a device that was recently removed from an array. This is only
-needed for arrays that have be built (i.e. with
-.BR --build ).
-For created arrays, devices are always re-added if that is possible.
-When re-adding a device, if nothing has changed on the array since the
-device was removed, no recovery is performed. Also, if the array has
-a write-intent bitmap, then the recovery performed after a re-add will
-be limited to those blocks which, according to the bitmap, might have
-changed since the device was removed.
+re\-add a device that was previous removed from an array.
+If the metadata on the device reports that it is a member of the
+array, and the slot that it used is still vacant, then the device will
+be added back to the array in the same position. This will normally
+cause the data for that device to be recovered. However based on the
+event count on the device, the recovery may only require sections that
+are flagged a write-intent bitmap to be recovered or may not require
+any recovery at all.
+
+When used on an array that has no metadata (i.e. it was built with
+.BR \-\-build)
+it will be assumed that bitmap-based recovery is enough to make the
+device fully consistent with the array.
+
+If the device name given is
+.B missing
+then mdadm will try to find any device that looks like it should be
+part of the array but isn't and will try to re\-add all such devices.
.TP
.BR \-r ", " \-\-remove
.TP
.BR \-\-write\-mostly
-Subsequent devices that are added or re-added will have the 'write-mostly'
+Subsequent devices that are added or re\-added will have the 'write-mostly'
flag set. This is only valid for RAID1 and means that the 'md' driver
will avoid reading from these devices if possible.
.TP
.BR \-\-readwrite
-Subsequent devices that are added or re-added will have the 'write-mostly'
+Subsequent devices that are added or re\-added will have the 'write-mostly'
flag cleared.
.P
operation.
If an array is using a write-intent bitmap, then devices which have
-been removed can be re-added in a way that avoids a full
+been removed can be re\-added in a way that avoids a full
reconstruction but instead just updates the blocks that have changed
since the device was removed. For arrays with persistent metadata
(superblocks) this is done automatically. For arrays created with
.B mdadm.conf
as requiring an external bitmap, that bitmap will be attached first.
+.TP
+.BR \-\-fail ", " \-f
+This allows the hot-plug system to remove devices that have fully disappeared
+from the kernel. It will first fail and then remove the device from any
+array it belongs to.
+The device name given should be a kernel device name such as "sda",
+not a name in
+.IR /dev .
+
.SH For Monitor mode:
.TP
.BR \-m ", " \-\-mail
When a device is added to an active array, mdadm checks to see if it
has metadata on it which suggests that it was recently a member of the
-array. If it does, it tried to "re-add" the device. If there have
+array. If it does, it tries to "re\-add" the device. If there have
been no changes since the device was removed, or if the array has a
write-intent bitmap which has recorded whatever changes there were,
then the device will immediately become a full member of the array and
.I component-device
.HP 12
Usage:
-.B mdadm \-\-incremental \-\-rebuild
+.B mdadm \-\-incremental \-\-fail
+.I component-device
+.HP 12
+Usage:
+.B mdadm \-\-incremental \-\-rebuild\-map
.HP 12
Usage:
.B mdadm \-\-incremental \-\-run \-\-scan
.B "mdadm \-\-incremental"
to be conditionally added to an appropriate array.
+Conversely, it can also be used with the
+.B \-\-fail
+flag to do just the opposite and find whatever array a particular device
+is part of and remove the device from that array.
+
If the device passed is a
.B CONTAINER
device created by a previous call to
Try to incorporate newly discovered device into some array as
appropriate.
-.B " mdadm \-\-incremental \-\-rebuild \-\-run \-\-scan"
+.B " mdadm \-\-incremental \-\-rebuild\-map \-\-run \-\-scan"
.br
Rebuild the array map from any current arrays, and then start any that
can be started.
projects / thirdparty / mdadm.git / blobdiff