Manual Reference Pages  - MULTIPATH.CONF (5)

NAME

multipath.conf - multipath daemon configuration file

CONTENTS

Description
Syntax
Authors

DESCRIPTION

multipath.conf is the configuration file for the multipath daemon. It is used to overwrite the built-in configuration table 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 values are given in the appropriate device or multipath sections.
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; default is 5
udev_dir directory where udev creates its device nodes; default is /dev
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_transport/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 /sbin/scsi_id -g -u -s
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_tpc /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.
mpath_prio_weighted %n|%h <regex1> <prio1> [<regex2> <prio2>] ...
  Generate a path priority based on the matching either the device name %n or the H:B:T:L %h of the devices against a series of regular expressions. WARNING: Both the device name and the H:B:T:L of a device can change when the node is rebooted, or the device driver is reloaded. If you use this callout it may be necessary to manually edit your regular expressions whenever either of these events occurs. NOTE: The regular expression must match the complete device name or H:B:T:L. For instance a regular expression of sda will only match a device named sda, not sdaa, sdab, etc. To match all of them, you would need to use the regular expression sda.*
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, values >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
.Default is 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.
max_fds Sets the maximum number of open file descriptors for the multipathd process. Setting this to max will cause multipathd to use the maximum number of open file descriptors allowed by the system.
verbosity Sets the verbosity level for the multipath and multipathd commands. It is overridden by the -v command line option. Valid values are from 0 to 6. Default is 2.
flush_on_last_del Setting this to yes will cause multipathd to disable queueing on a multipath device when the last path to the device has been deleted. Default is no
queue_without_daemon
  Setting this to no will cause multipathd to disable queueing for all multipath devices when it is shutdown. Default is yes
bindings_file Sets the location for the multipath bindings file that is used with the user_friendly_names option. Default is /etc/multipath_bindings
mode The mode to use for the multipath device nodes, in octal.
uid The numeric uid to use for the multipath device nodes.
gid The numeric gid to use for the multipath device nodes.
user_friendly_names
  If set to yes , using the bindings file /var/lib/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

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
prio_callout
path_selector
failback
no_path_retry
rr_min_io
rr_weight
flush_on_last_del
mode
uid
gid
 

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 implemented:
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
flush_on_last_del
 

SEE ALSO

udev(8), dmsetup(8) multipath(8) multipathd(8)

AUTHORS

multipath was developed by Christophe Varoqui, <christophe.varoqui@free.fr> and others.


MULTIPATH.CONF (5) 30 November 2006
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