MULTIPATHD(8)

NAME
multipathd - Multipath daemon.

SYNOPSIS
multipathd [-d] [-s] [-v verbosity] [-B] [-w]

multipathd [-v verbosity] -kcommand

multipathd [-v verbosity] -k

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. With the -k option, multipathd acts as a client utility that sends commands to a running instance of the multipathd daemon (see COMMANDS below).

OPTIONS

-d  Foreground Mode. Don't daemonize, and print all messages to stdout and stderr.

-s  Suppress timestamps. Do not prefix logging messages with a timestamp.

-v level
    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.

-B  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.

-kcommand
    multipathd executes the given command (see COMMANDS below). If the command contains whitespace or shell special characters, it needs to be quoted like in multipathd -k'show topology'. No whitespace is allowed between the -k and the command string. Commands can also be issued without using -k. In this case, the command string should not be quoted. Command arguments that contain whitespace or special characters still need to be quoted, like in multipathd show paths format "%n %w"

-k  multipathd executes the multipathc interactive shell for entering commands (see COMMANDS below).

-n  IGNORED. Use the option find_multipaths to control the treatment of newly detected devices by multipathd. See multipath.conf(5).

-w  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 separate thread for each device.

COMMUNICATING WITH MULTIPATHD
In addition to the multipathd CLI, the libmpathcmd library can be used to send commands (see COMMANDS below) to the multipathd daemon from other programs. By default, multipathd listens on both the @/org/kernel/linux/storage/multipathd abstract namespace socket and the /run/multipathd.socket socket file. libmpathcmd will use either of these sockets to connect to multipathd. The socket file can be useful to communicate with multipathd from different namespaces since it can be bind mounted in them, unlike the abstract namespace socket. Multipathd will accept list|show commands from any user. All other commands must be issued by root. It is possible to change the sockets that multipathd listens on. If multipathd.socket is running, multipathd will use the sockets it listens on. A maximum of two sockets can be defined by multipathd.socket, and by default it listens on @/org/kernel/linux/storage/multipathd and /run/multipathd.socket. If multipathd.socket is not running, a single socket can be configured for listening on by setting the MULTIPATH_SOCKET_NAME environment variable when starting multipathd. This environment variable must also be set to make multipathd CLI commands (or any other program using libmpathcmd) connect to the multipathd daemon using a non-default socket, regardless of whether that socket was set for the daemon using multipathd.socket or the MULTIPATH_SOCKET_NAME environment variable.

COMMANDS

The following commands can be used in interactive mode:

list|show paths
    Show the paths that multipathd is monitoring, and their state.

list|show paths [raw] format $format
    Show the paths that multipathd is monitoring, using a format string with path format wildcards. Adding raw will remove the headers and alignment padding from the output. See "Path format wildcards" below.

list|show path $path
    Show whether path $path is offline or running.

list|show maps|multipaths
    Show the multipath devices that the multipathd is monitoring.

list|show maps|multipaths [raw] format $format
    Show the status of all multipath devices that the multipathd is monitoring, using a format string with multipath format wildcards. Adding raw will remove the headers and alignment padding from the output. See "Multipath format wildcards" below.

list|show maps|multipaths status
    Show the status of all multipath devices that the multipathd is monitoring.

list|show maps|multipaths stats
    Show some statistics of all multipath devices that the multipathd is monitoring.

list|show maps|multipaths topology
    Show the current multipath topology. Same as 'multipath -ll'.

list|show maps|multipaths json
    Show information about all multipath devices in JSON format.

list|show topology
    Show the current multipath topology. Same as 'multipath -ll'.

list|show map|multipath $map topology
    Show topology of a single multipath device specified by $map, for example 36005076303ffc56200000000000010aa. This map could be obtained from 'list maps'.

list|show map|multipath $map [raw] format $format.
    Show the status of multipath device $map, using a format string with multipath format wildcards. Adding raw will remove the headers and alignment padding from the output. See "Multipath format wildcards" below.

list|show map|multipath $map json
    Show information about multipath device $map in JSON format.

list|show wildcards
    Show the format wildcards used in interactive commands taking $format. See "Format Wildcards" below.

list|show config
    Show the currently used configuration, derived from default values and values specified within the configuration file /etc/multipath.conf.

list|show config local
    Show the currently used configuration like show config, but limiting the devices section to those devices that are actually present in the system.

list|show blacklist
    Show the currently used blacklist rules, derived from default values and values specified within the configuration file /etc/multipath.conf.

list|show devices
    Show all available block devices by name including the information if they are blacklisted or not.

list|show status
    Show the number of path checkers in each possible state, the number of monitored paths, and whether multipathd is currently handling a uevent.

list|show daemon
    Show the current state of the multipathd daemon.

reset maps|multipaths stats
    Reset the statistics of all multipath devices.

reset map|multipath $map stats
    Reset the statistics of multipath device $map.

add path $path
    Add a path to the list of monitored paths. $path is as listed in /sys/block (e.g. sda).

remove|del path $path
    Stop monitoring a path. $path is as listed in /sys/block (e.g. sda).

add map|multipath $map
    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).

remove|del maps|multipaths
    Remove all multipath devices.

remove|del map|multipath $map
    Remove the multipath device $map.

resize map|multipath $map
    Resizes map $map to the given size.

switch|switchgroup map|multipath $map group $group
    Force a multipath device to switch to a specific path group. $group is the path group index, starting with 1.

reconfigure
    Rereads the configuration, and reloads all changed multipath devices. This also happens at startup, when the service is reload, or when a SIGHUP is received.

reconfigure all
    Rereads the configuration, and reloads all multipath devices regardless of whether or not they have changed. This also happens when multipath -r is run.

suspend map|multipath $map
    Sets map $map into suspend state.

resume map|multipath $map
    Resumes map $map from suspend state.

reset map|multipath $map
    Reassign existing device-mapper table(s) use the multipath device, instead of its path devices.

reload map|multipath $map
    Reload a multipath device.

fail path $path
    Sets path $path into failed state.

reinstate path $path
    Resumes path $path from failed state.

disablequeueing maps|multipaths
    Disable queueing on all multipath devices.

restorequeueing maps|multipaths
    Restore queueing to the configured no_path_retry setting on all multipath devices whose queueing has been previously disabled by the disablequeueing command. Note: If no_path_path_retry is set to queue for a limited number of retries after all paths have failed, this will not enable queueing if there are no active paths.

disablequeueing map|multipath $map
    Disable queuing on multipathed map $map.

restorequeueing map|multipath $map
    restore queueing to the configured no_path_retry setting on multipathed map $map whose queueing has been previously disabled by the disablequeueing command. Note: If no_path_path_retry is set to queue for a limited number of retries after all paths have failed, this will not enable queueing if there are no active paths.

forcequeueing daemon
    Forces multipathd into queue_without_daemon mode, so that no_path_retry queueing will not be disabled when the daemon stops.

restorequeueing daemon
    Restores configured queue_without_daemon mode.

setprstatus map|multipath $map
    Enable persistent reservation management on $map.

setprstatus map|multipath $map pathlist $pathlist
    Enable persistent reservation management on $map, and notify multipathd of the paths that have been registered, so it doesn't attempt to re-register them.

unsetprstatus map|multipath $map
    Disable persistent reservation management on $map.

getprstatus map|multipath $map
    Get the current persistent reservation management status of $map.

getprkey map|multipath $map
    Get the current persistent reservation key associated with $map.

setprkey map|multipath $map key $key
    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.

unsetprkey map|multipath $map
    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.

setmarginal path $path
    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).

unsetmarginal path $path
    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).

unsetmarginal map $map
    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).

quit|exit
    End interactive session.

shutdown
    Stop multipathd.

Format Wildcards
Multipathd commands that take a $format option require a format string. This string controls how a device is printed and should include format wildcards. When the devices are printed, these wildcards will be replaced by the appropriate device information. The following wildcards are supported.

Multipath format wildcards

    %n  The device name.

    %w  The device WWID (uuid).

    %d  The device sysfs name (dm-<minor_nr>).

    %F  The device failback setting. For deferred failbacks, it will either include the configured time if a deferred failback is not in progress, or it will show the current progress of a deferred failback in seconds.

    %Q  The device no_path_retry setting. If no_path_retry is set to a number of retries, it will either print the configured number of checker retries if the device is not in recovery mode, the number of seconds until queueing is disabled if the device is queueing in recovery mode, or off if the device has disabled queueing.

    %N  The number of active paths for the device.

    %r  The device write-protect setting, either ro or rw.

    %t  The state of the device in device-mapper. suspend if the devices is suspended, and active otherwise.

    %S  The device size, using the suffixes K, M, G, T, and P, to stand for kilobytes, megabytes, gigabytes, terabytes, and petabytes, respectively.

    %f  The "features" string of the device-mapper table in the kernel.

    %x  The number of times the device has entered a state where it will fail IO. This is an alias for the %4 wildcard. This value can be reset with the 'reset map $map stats' command.

    %h  The device table hardware handler string.

    %A  The last action multipathd took on the device. This wildcard is for debugging use, as understanding its meaning requires looking at the code.

    %0  The number of times a path in the device has failed. This value can be reset with the 'reset map $map stats' command.

    %1  The number of times multipathd has initiated a pathgroup switch for the device. This value can be reset with the 'reset map $map stats' command.

    %2  The number of times multipathd has loaded a new table for the device. This value can be reset with the 'reset map $map stats' command.

    %3  The approximate number of seconds that multipathd has spent queueing with no usable paths. This value can be reset with the 'reset map $map stats' command.

    %4  The number of times the device has entered a state where it will fail IO. This is an alias for the %x wildcard. This value can be reset with the 'reset map $map stats' command.

    %s  The vendor/product string for the device.

    %v  The array vendor string for the device.

    %p  The array product string for the device.

    %e  The array firmware revision string for the device.

    %G  The foreign library used for the device, or -- for native device-mapper multipath devices. See "FOREIGN MULTIPATH SUPPORT" in /etc/multipath.conf(5).

    %g  Data from vendor specific vpd pages for the device, if any. Currently multipathd supports VPD page 0xc0 for HPE 3PAR / Primera / Alletra storage arrays.

    %k  The actual max_sectors_kb setting for the device (which may be different from the configured one).

Path format wildcards

    %w  The device WWID (uuid).

    %i  The device Host:Channel:Id:Lun for SCSI devices. The device "Controller Instance Number":"Controller ID":"Namespace Instance Number":"Namespace ID" for NVMe devices. The Controller and Namespace Instance Numbers match the NVMe device name: "nvme<Controller_Instance_Number>n<Namespace_Instance_Number>"

    %d  The device sysfs name.

    %D  The device major:minor

    %t  The device-mapper state of the device, either active or failed.

    %o  The offline state of the device. This shows "offline" if the device's "state" attribute in sysfs is "offline" (for SCSI) or "dead" (for NVMe). For all other sysfs states, it shows "running".

    %T  The multipathd path checker state of the device. The possible states are:

        ready
            The device is ready to handle IO.

        faulty
            The device is unusable.

        shaky
            The device is not able to handle IO but can still be accessed to check the priority.

        ghost
            The device is in stand-by state.

        i/o pending
            The checker is in the process of determining the device state.

        i/o timeout
            The path checker has timed out, failing the device.

        delayed
            The device appears usable, but it being delayed for marginal path checking.

        undef
            The device either is not part of a multipath device, or its path checker has not yet run.

    %s  The vendor/product/revision string for the device.

    %c  The name of the device's path checking algorithm

    %C  The progress towards the next path checker run on the device in seconds.

    %p  The device priority.

    %S  The device size, using the suffixes K, M, G, T, and P, to stand for kilobytes, megabytes, gigabytes, terabytes, and petabytes, respectively.

    %z  The device serial number.

    %M  The device marginal state, either marginal or normal.

    %m  The multipath device that this device is a path of, or [offline] if this device could not be added to a device because it is offline or [orphan] if it is not part of any multipath device.

    %N  The host World Wide Node Name (WWNN) of the device, if any.

    %n  The target World Wide Node Name (WWNN) of the device, if any.

    %R  The host World Wide Port Name (WWPN) of the device, if any.

    %r  The target World Wide Port Name (WWPN) of the device, if any.

    %a  The host adapter name for the device (only SCSI devices).

    %G  The foreign library used for the device, or -- for native device-mapper multipath devices. See "FOREIGN MULTIPATH SUPPORT" in /etc/multipath.conf(5).

    %g  Data from vendor specific vpd pages for the device, if any. Currently multipathd supports VPD page 0xc0 for HPE 3PAR / Primera / Alletra storage arrays.

    %0  The number of times this device has failed.

    %P  The device protocol. See /etc/multipath.conf(5).

    %I  The device initialization state. Devices that have been fully initialized are shown as ok.

    %L  The device SCSI LUN ID in hexadecimal format. This is only meaningful for SCSI devices.

    %A  The ALUA Target Port Group ID for the device, if applicable.

    %k  The actual max_sectors_kb setting for the device (which may be different than the configured one).

SYSTEMD INTEGRATION
When compiled with systemd support two systemd service files are installed, multipathd.service and multipathd.socket. If enabled, 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:

WatchdogSec=
    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.

OOMScoreAdjust=
    Overrides the internal OOM adjust mechanism.

LimitNOFILE=
    Overrides the max_fds configuration setting.

SEE ALSO
multipathc(8), multipath(8), kpartx(8)
sd_notify(3), systemd.service(5).

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