multipath - Device mapper target autoconfig.
multipath [
-v level]
[
-B|
-d|
-i|
-q|
-r]
[
-b file] [
-p policy]
[
device]
multipath [
-v level]
[
-R retries]
-f device
multipath [
-v level]
[
-R retries]
-F
multipath [
-v level] [
-l|
-ll]
[
device]
multipath [
-v level] [
-a|
-w]
device
multipath [
-v level]
-W
multipath [
-v level] [
-i]
[
-c|
-C]
device
multipath [
-v level] [
-i]
[
-u|
-U]
multipath [
-h|
-t|
-T]
multipath is used to detect and coalesce multiple paths to devices, for
fail-over or performance reasons.
The
device argument restricts
multipath's operation to devices
matching the given expression. The argument may refer either to a multipath
map or to its components ("paths"). The expression may be in one of
the following formats:
- device node
- file name of a device node, e.g. /dev/dm-10 or
/dev/sda. If the node refers to an existing device mapper device
representing a multipath map, this selects the map or its paths, depending
on the operation mode. Otherwise, it selects a path device.
- device ID
- kernel device number specified by major:minor numbers, e.g.
65:16. This format can only be used for path devices.
- WWID
- a World Wide Identifier matching a multipath map or its
paths. To list WWIDs of devices present in the system, use e.g. the
command " multipath -d -v3 2>/dev/null".
The default operation mode is to detect and set up multipath maps from the
devices found in the system. Other operation modes are chosen by using one of
the following command line switches:
- -f
- Flush (remove) a multipath device map specified as
parameter, if unused. This operation is delegated to the multipathd daemon
if it's running.
- -F
- Flush (remove) all unused multipath device maps. This
operation is delegated to the multipathd daemon if it's running.
- -l
- Show ("list") the current multipath topology from
information fetched in sysfs and the device mapper.
- -ll
- Show ("list") the current multipath topology from
all available information (sysfs, the device mapper, path checkers
...).
- -a
- Add the WWID for the specified device to the WWIDs
file.
- -w
- Remove the WWID for the specified device from the WWIDs
file.
- -W
- Reset the WWIDs file to only include the current multipath
devices.
- -c
- Check if a block device should be a path in a multipath
device.
- -C
- Check if a multipath device has usable paths. This can be
used to test whether or not I/O on this device is likely to succeed. The
command itself doesn't attempt to do I/O on the device.
- -u
- Check if the device specified in the program environment
should be a path in a multipath device.
- -U
- Check if the device specified in the program environment is
a multipath device with usable paths. See -C.
- -h
- Print usage text.
- -t
- Display the currently used multipathd configuration.
- -T
- Display the currently used multipathd configuration,
limiting the output to those devices actually present in the system. This
can be used a template for creating multipath.conf.
-
-v level
- Verbosity of information printed to stdout in default and
"list" operation modes. The default level is -v 2.
- 0
- Nothing is printed.
- 1
- In default mode, Names/WWIDs of created or modified
multipath maps are printed. In list mode, WWIDs of all multipath maps are
printed.
- 2
- In default mode, Topology of created or modified multipath
maps is printed. In list mode, topology of all multipath maps is
printed.
- 3
- All detected paths and the topology of all multipath maps
are printed.
The verbosity level also controls the level of log and debug messages printed to
stderr. The default level corresponds to
LOG_NOTICE (important
messages that shouldn't be missed in normal operation).
- -d
- Dry run, do not create or update devmaps.
- -e
- Enable all foreign libraries. This overrides the
enable_foreign option from multipath.conf(5).
- -i
- Ignore WWIDs file when processing devices. If
find_multipaths strict or find_multipaths no is set in
multipath.conf, multipath only considers devices that are listed in
the WWIDs file. This option overrides that behavior. For other values of
find_multipaths, this option has no effect. See the description of
find_multipaths in multipath.conf(5). This option should
only be used in rare circumstances.
- -B
- Treat the bindings file as read only.
-
-b file
- Set user_friendly_names bindings file location. The
default is /etc/multipath/bindings.
- -q
- Don't unset the device mapper feature
queue_if_no_path for multipath maps. Normally, multipath
would do so if multipathd is not running, because only a running
multipath daemon guarantees that unusable paths are reinstated when they
become usable again.
-
-p policy
- Force new maps to use the specified policy, overriding the
configuration in multipath.conf(5). The possible values for
policy are the same as the values for path_grouping_policy
in multipath.conf(5). Existing maps are not modified.
- -r
- Force a reload of all existing multipath maps. This command
is delegated to the multipathd daemon if it's running. In this case, other
command line switches of the multipath command have no effect.
-
-R retries
- Number of times to retry flushing multipath devices that
are in use. The default is 0.
multipathd(8),
multipath.conf(5),
kpartx(8),
udev(8),
dmsetup(8),
hotplug(8).
multipath-tools was developed by Christophe Varoqui
<
[email protected]> and others.