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.
multipath-tools was developed by Christophe Varoqui
<christophe.varoqui@opensvc.com> and others.