05-31-2016
Yes. If we have external storage devices attached to the server, like 3PAR, etc then for the device to be able to communicate with the server, and to configure the drives for mounting we need multipathing on the OS.
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LEARN ABOUT SUSE
multipathd
MULTIPATHD(8) System Manager's Manual MULTIPATHD(8)
NAME
multipathd - multipath daemon
SYNOPSIS
multipathd [options]
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 config 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.
OPTIONS
-d Forground Mode. Don't daemonize, and print all messages to stdout and stderr.
-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.
-k multipathd will enter interactive mode. From this mode, the available commands can be viewed by entering "help". When you are fin-
ished entering commands, press CTRL-D to quit.
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 maps|multipaths
Show the multipath devices that the multipathd is monitoring.
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 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, e.g. 36005076303ffc56200000000000010aa. This map could be obtained
from "list maps".
list|show config
Show the currently used configuration, derived from default values and values specified within the configuration file /etc/multi-
path.conf.
list|show blacklist
Show the currently used blacklist rules, derived from default values and values specified within the configuration file /etc/multi-
path.conf.
list|show devices
Show all available block devices by name including the information if they are blacklisted or not.
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 $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 map $map
Stop monitoring a multipath device.
resize map|multipath $map
Resizes map $map to the given size
switch|switchgroup map $map group $group
Force a multipath device to switch to a specific path group. $group is the path group index, starting with 1.
reconfigure
Reconfigures the multipaths. This should be triggered automatically after any hotplug event.
suspend map|multipath $map
Sets map $map into suspend state.
resume map|multipath $map
Resumes map $map from suspend state.
fail path $path
Sets path $path into failed state.
reinstate path $path
Resumes path $path from failed state.
disablequeueing map|multipath $map
Disabled queuing on multipathed map $map
restorequeueing map|multipath $map
Restore queuing on multipahted map $map
SEE ALSO
multipath(8) kpartx(8) hotplug(8)
AUTHORS
multipathd was developed by Christophe Varoqui, <christophe.varoqui@free.fr> and others.
Linux Administrator's Manual November 2009 MULTIPATHD(8)