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MULTIPATH.CONF(5) MULTIPATH.CONF(5)
NAME
multipath.conf - multipath daemon configuration file
DESCRIPTION
multipath.conf is the configuration file for the multipath daemon. It is used to overwrite the built-in configuration ta-
ble of multipathd. Any line whose first non-white-space character is a '#' is considered a comment line. Empty lines are
ignored.
SYNTAX
The configuration file contains entries of the form:
<section> {
<attribute> <value>
...
<subsection> {
<attribute> <value>
...
}
}
Each section contains one or more attributes or subsections. The recognized keywords for attributes or subsections depend
on the section in which they occor.
The following section keywords are recognized:
defaults This section defines default values for attributes which are used whenever no specific setting is given.
blacklist This section defines which devices should be excluded from the multipath topology discovery.
blacklist_exceptions
This section defines which devices should be included in the multipath topology discovery, despite being
listed in the blacklist section.
multipaths This section defines the multipath topologies. They are indexed by a World Wide Identifier(wwid), which
is the result of the getuid_callout program.
devices This section defines the device-specific settings.
defaults section
The defaults section recognizes the following keywords:
polling_interval interval between two path checks in seconds For properly functioning paths, the interval between checks
will gradually increase to (4 * polling_interval); default is 5
udev_dir directory where udev creates its device nodes; default is /dev
verbosity default verbosity. Higher values increase the verbosity level. Valid levels are between 0 and 6; default
is 2
selector The default path selector algorithm to use; they are offered by the kernel multipath target. The only
currently implemented is round-robin 0
path_grouping_policy
The default path grouping policy to apply to unspecified multipaths. Possible values are
failover 1 path per priority group
multibus all paths in 1 priority group
group_by_serial
1 priority group per serial number
group_by_prio
1 priority group per priority value. Priorities are determined by callout programs specified
as a global, per-controller or per-multipath option in the configuration file.
group_by_node_name
1 priority group per target node name. Target node names are fetched in /sys/class/fc_trans-
port/target*/node_name.
Default value is multibus.
getuid_callout The default program and args to callout to obtain a unique path identifier. Should be specified with an
absolute path. Default value is /lib/udev/scsi_id --whitelisted --device=/dev/%n
prio_callout The default program and args to callout to obtain a path priority value. The specified program will be
executed and should return a numeric value specifying the relative priority of this path. Higher number
have a higher priority. A '%n' in the command line will be expanded to the device name, a '%b' will be
expanded to the device number in major:minor format. none is a valid value. Currently the following
path priority programs are implemented:
mpath_prio_emc /dev/%n
Generate the path priority for EMC arrays
mpath_prio_alua /dev/%n
Generate the path priority based on the SCSI-3 ALUA settings.
mpath_prio_netapp /dev/%n
Generate the path priority for NetApp arrays.
mpath_prio_rdac /dev/%n
Generate the path priority for LSI/Engenio RDAC controller.
mpath_prio_hp_sw /dev/%n
Generate the path priority for Compaq/HP controller in active/standby mode.
mpath_prio_hds_modular %b
Generate the path priority for Hitachi HDS Modular storage arrays.
Default value is none.
features Specify any device-mapper features to be used. The most common of these features is 1 queue_if_no_path
Note that this can also be set via the no_path_retry keyword.
path_checker The default method used to determine the paths' state. Possible values are
readsector0 Read the first sector of the device
tur Issue a TEST UNIT READY command to the device.
emc_clariion
Query the EMC Clariion specific EVPD page 0xC0 to determine the path state.
hp_sw Check the path state for HP storage arrays with Active/Standby firmware.
rdac Check the path state for LSI/Engenio RDAC storage controller.
directio Read the first sector with direct I/O.
Default value is readsector0.
failback Tell the daemon to manage path group failback, or not to. 0 or immediate means immediate failback, val-
ues >0 means deferred failback (in seconds). manual means no failback. Default value is manual
rr_min_io The number of IO to route to a path before switching to the next in the same path group. Default is 1000
rr_weight If set to priorities the multipath configurator will assign path weights as "path prio * rr_min_io".
Possible values are priorities or uniform uniform
no_path_retry Specify the number of retries until disable queueing, or fail for immediate failure (no queueing), queue
for never stop queueing. Default is 0.
user_friendly_names
If set to yes , using the bindings file /etc/multipath/bindings to assign a persistent and unique alias
to the multipath, in the form of mpath<n>. If set to no use the WWID as the alias. In either case this
be will be overriden by any specific aliases in the multipaths section. Default is no
max_fds Specify the maximum number of file descriptors that can be opened by multipath and multipathd. This is
equivalent to ulimit -n. A value of max will set this to the system limit from /proc/sys/fs/nr_open. If
this is not set, the maximum number of open fds is taken from the calling process. It is usually 1024.
To be safe, this should be set to the maximum number of paths plus 32, if that number is greated than
1024.
fast_io_fail_tmo Specify the number of seconds the scsi layer will wait after a problem has been detected on a FC remote
port before failing IO to devices on that remote port. This should be smaller than dev_loss_tmo. Set-
ting this to off will disable the timeout.
dev_loss_tmo Specify the number of seconds the scsi layer will wait after a problem has been detected on a FC remote
port before removing it from the system.
blacklist section
The blacklist section is used to exclude specific device from inclusion in the multipath topology. It is most commonly
used to exclude local disks or LUNs for the array controller.
The following keywords are recognized:
wwid The World Wide Identification of a device.
devnode Regular expression of the device nodes to be excluded.
device Subsection for the device description. This subsection recognizes the vendor and product keywords. For a
full description of these keywords please see the devices section description.
blacklist_exceptions section
The blacklist_exceptions section is used to revert the actions of the blacklist section, ie to include specific device in
the multipath topology. This allows to selectively include devices which would normally be excluded via the blacklist
section.
The following keywords are recognized:
wwid The World Wide Identification of a device.
devnode Regular expression of the device nodes to be excluded.
device Subsection for the device description. This subsection recognizes the vendor and product keywords. For a
full description of these keywords please see the devices section description.
multipaths section
The only recognized attribute for the multipaths section is the multipath subsection.
The multipath subsection recognizes the following attributes:
wwid Index of the container. Mandatory for this subsection.
alias (Optional) symbolic name for the multipath map.
The following attributes are optional; if not set the default values are taken from the defaults section:
path_grouping_policy
path_selector
failback
no_path_retry
rr_min_io
devices section
The only recognized attribute for the devices section is the device subsection.
The device subsection recognizes the following attributes:
vendor (Mandatory) Vendor identifier
product (Mandatory) Product identifier
product_blacklist
Product strings to blacklist for this vendor
hardware_handler (Optional) The hardware handler to use for this device type. The following hardware handler are imple-
mented:
1 emc Hardware handler for EMC storage arrays.
The following attributes are optional; if not set the default values are taken from the defaults section:
path_grouping_policy
getuid_callout
path_selector
path_checker
features
prio_callout
failback
rr_weight
no_path_retry
rr_min_io
fast_io_fail_tmo
dev_loss_tmo
KNOWN ISSUES
The usage of queue_if_no_path option can lead to D state processes being hung and not killable in situations where all
the paths to the LUN go offline. It is advisable to use the no_path_retry option instead.
SEE ALSO
udev(8), dmsetup(8) multipath(8) multipathd(8)
AUTHORS
multipath was developed by Christophe Varoqui, <christophe.varoquiATfree.fr> and others.
30 November 2006 MULTIPATH.CONF(5)
