2. EL 8
  3. device-mapper-multipath
  4. multipathd(8)

Scroll to navigation

MULTIPATHD(8) System Manager's Manual MULTIPATHD(8)

NAME

multipathd - Multipath daemon.

SYNOPSIS

multipathd [-d|-k] [-s] [-v verbosity] [-B] [-w]

DESCRIPTION

The multipathd daemon is in charge of checking for failed paths. When this happens, it will reconfigure the multipath map the path belongs to, so that this map regains its maximum performance and redundancy.

This daemon executes the external multipath tool when events occur. In turn, the multipath tool signals the multipathd daemon when it is done with devmap reconfiguration, so that it can refresh its failed path list.

In this Linux distribution, multipathd does not run unless a /etc/multipath.conf file exists.

OPTIONS

Foreground Mode. Don't daemonize, and print all messages to stdout and stderr.
Suppress timestamps. Do not prefix logging messages with a timestamp.
Verbosity level. Print additional information while running multipathd. A level of 0 means only print errors. A level of 3 or greater prints debugging information as well.
Read-only bindings file. multipathd will not write to the user_friendly_names bindings file. If a user_friendly_name doesn't already exist for a device, it will use its WWID as its alias.
multipathd will enter interactive mode. From this mode, the available commands can be viewed by entering 'help'. When you are finished entering commands, press CTRL-D to quit.
IGNORED. Use the option find_multipaths to control the treatment of newly detected devices by multipathd. See multipath.conf(5).
Since kernel 4.14 a new device-mapper event polling interface is used for updating multipath devices on dmevents. Use this flag to force it to use the old event waiting method, based on creating a seperate thread for each device.

COMMANDS

Show the paths that multipathd is monitoring, and their state.
Show the paths that multipathd is monitoring, using a format string with path format wildcards.
Show the multipath devices that the multipathd is monitoring.
Show the status of all multipath devices that the multipathd is monitoring, using a format string with multipath format wildcards.
Show the status of all multipath devices that the multipathd is monitoring.
Show some statistics of all multipath devices that the multipathd is monitoring.
Show the current multipath topology. Same as 'multipath -ll'.
Show the current multipath topology. Same as 'multipath -ll'.
Show topology of a single multipath device specified by $map, for example 36005076303ffc56200000000000010aa. This map could be obtained from 'list maps'.
Show the format wildcards used in interactive commands taking $format.
Show the currently used configuration, derived from default values and values specified within the configuration file /etc/multipath.conf.
Show the currently used configuration like show config, but limiting the devices section to those devices that are actually present in the system.
Show the currently used blacklist rules, derived from default values and values specified within the configuration file /etc/multipath.conf.
Show all available block devices by name including the information if they are blacklisted or not.
Show the number of path checkers in each possible state, the number of monitored paths, and whether multipathd is currently handling a uevent.
Show the current state of the multipathd daemon.
Add a path to the list of monitored paths. $path is as listed in /sys/block (e.g. sda).
Stop monitoring a path. $path is as listed in /sys/block (e.g. sda).
Add a multipath device to the list of monitored devices. $map can either be a device-mapper device as listed in /sys/block (e.g. dm-0) or it can be the alias for the multipath device (e.g. mpath1) or the uid of the multipath device (e.g. 36005076303ffc56200000000000010aa).
Stop monitoring a multipath device.
Resizes map $map to the given size.
Force a multipath device to switch to a specific path group. $group is the path group index, starting with 1.
Reconfigures the multipaths. This should be triggered automatically after anyi hotplug event.
Sets map $map into suspend state.
Resumes map $map from suspend state.
Reassign existing device-mapper table(s) use use the multipath device, instead of its path devices.
Reload a multipath device.
Sets path $path into failed state.
Resumes path $path from failed state.
Disable queueing on all multipath devices.
Restore queueing on all multipath devices.
Disable queuing on multipathed map $map.
Restore queuing on multipahted map $map.
Forces multipathd into queue_without_daemon mode, so that no_path_retry queueing will not be disabled when the daemon stops.
Restores configured queue_without_daemon mode.
Enable persistent reservation management on $map.
Disable persistent reservation management on $map.
Get the current persistent reservation management status of $map.
Get the current persistent reservation key associated with $map.
Set the persistent reservation key associated with $map to $key in the prkeys_file. This key will only be used by multipathd if reservation_key is set to file in /etc/multipath.conf.
Remove the persistent reservation key associated with $map from the prkeys_file. This will only unset the key used by multipathd if reservation_key is set to file in /etc/multipath.conf.
move $path to a marginal pathgroup. The path will remain in the marginal path group until unsetmarginal is called. This command will only work if marginal_pathgroups is enabled and there is no Shaky paths detection method configured (see the multipath.conf man page for details).
return marginal path $path to its normal pathgroup. This command will only work if marginal_pathgroups is enabled and there is no Shaky paths detection method configured (see the multipath.conf man page for details).
return all marginal paths in $map to their normal pathgroups. This command will only work if marginal_pathgroups is enabled and there is no Shaky paths detection method configured (see the multipath.conf man page for details).
End interactive session.
Stop multipathd.

SYSTEMD INTEGRATION

When compiled with systemd support two systemd service files are installed, multipathd.service and multipathd.socket The multipathd.socket service instructs systemd to intercept the CLI command socket, so that any call to the CLI interface will start-up the daemon if required. The multipathd.service file carries the definitions for controlling the multipath daemon. The daemon itself uses the sd_notify(3) interface to communicate with systemd. The following unit keywords are recognized:

Enables the internal watchdog from systemd. multipath will send a notification via sd_notify(3) to systemd to reset the watchdog. If specified the polling_interval and max_polling_interval settings will be overridden by the watchdog settings. Please note that systemd prior to version 207 has issues which prevent the systemd-provided watchdog from working correctly. So the watchdog is not enabled per default, but has to be enabled manually by updating the multipathd.service file.
Overrides the internal OOM adjust mechanism.
Overrides the max_fds configuration setting.

SEE ALSO

multipath(8), kpartx(8), sd_notify(3), system.service(5).

AUTHORS

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

2016-10-27 Linux