-
Language:
English
-
Language:
English
4.3. Configuration File Defaults
The
/etc/multipath.conf
configuration file includes a defaults
section that sets the user_friendly_names
parameter to yes
, as follows.
defaults { user_friendly_names yes }
This overwrites the default value of the
user_friendly_names
parameter.
The configuration file includes a template of configuration defaults. This section is commented out, as follows.
#defaults { # udev_dir /dev # polling_interval 10 # selector "round-robin 0" # path_grouping_policy multibus # getuid_callout "/sbin/scsi_id -g -u -s /block/%n" # prio_callout /bin/true # path_checker readsector0 # rr_min_io 100 # rr_weight priorities # failback immediate # no_path_retry fail # user_friendly_name yes #}
To overwrite the default value for any of the configuration parameters, you can copy the relevant line from this template into the
defaults
section and uncomment it. For example, to overwrite the path_grouping_policy
parameter so that it is multibus
rather than the default value of failover
, copy the appropriate line from the template to the initial defaults
section of the configuration file, and uncomment it, as follows.
defaults { user_friendly_names yes path_grouping_policy multibus }
Table 4.1, “Multipath Configuration Defaults” describes the attributes that are set in the
defaults
section of the multipath.conf
configuration file. These values are used by DM-Multipath unless they are overwritten by the attributes specified in the devices
and multipaths
sections of the multipath.conf
file.
Table 4.1. Multipath Configuration Defaults
Attribute | Description | ||||||
---|---|---|---|---|---|---|---|
udev_dir | Specifies the directory where udev device nodes are created. The default value is /udev . | ||||||
polling_interval | Specifies the interval between two path checks in seconds. The default value is 5. | ||||||
selector | Specifies the default algorithm to use in determining what path to use for the next I/O operation. The default value is round-robin 0 . | ||||||
path_grouping_policy | Specifies the default path grouping policy to apply to unspecified multipaths. Possible values include:
| ||||||
getuid_callout | Specifies the default program and arguments to call out to obtain a unique path identifier. An absolute path is required.
| ||||||
prio_callout | Specifies the default program and arguments to call out to obtain a path priority value. For example, the ALUA bits in SPC-3 provide an exploitable prio value for example. "none" is a valid value. The default value is no callout, indicating all paths are equal | ||||||
features | Specifies the default extra features of multipath devices. The only existing feature is queue_if_no_path . The default value is (null). | ||||||
path_checker | Specifies the default method used to determine the state of the paths. Possible values include: readsector0 , tur , emc_clariion , hp_sw , and directio . The default value is readsector0 . | ||||||
failback | Specifies path group failback.
| ||||||
rr_min_io | Specifies the number of I/O requests to route to a path before switching to the next path in the current path group. The default value is 1000. | ||||||
max_fds | (RHEL 4.7 and later) Sets the maximum number of open file descriptors for the multipathd process. A value of max sets the number of open file descriptors to the system maximum. | ||||||
rr_weight | If set to priorities , then instead of sending rr_min_io requests to a path before calling selector to choose the next path, the number of requests to send is determined by rr_min_io times the path's priority, as determined by the prio_callout program. Currently, there are priority callouts only for devices that use the group_by_prio path grouping policy, which means that all the paths in a path group will always have the same priority.
| ||||||
no_path_retry | A numeric value for this attribute specifies the number of times the system should attempt to use a failed path before disabling queueing.
| ||||||
flush_on_last_del | (RHEL 4.7 and later) If set to yes , the multipathd daemon will disable queueing when the last path to a device has been deleted. The default value is no . | ||||||
user_friendly_names | If set to yes , specifies that the system should 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 , specifies that the system should use use the WWID as the alias for the multipath. In either case, what is specified here will be overridden by any device-specific aliases you specify in the multipaths section of the configuration file. The default value is no . | ||||||
bindings_file | (RHEL 4.6 and later) The location of the bindings file that is used with the user_friendly_names option. The default value is /var/lib/multipath/bindings . | ||||||
mode | (RHEL 4.7 and later) The mode to use for the multipath device nodes, in octal. The default value is determined by the process. | ||||||
uid | (RHEL 4.7 and later) The user ID to use for the multipath device nodes. You must use the numeric user ID. The default value is determined by the process. | ||||||
gid | (RHEL 4.7 and later) The group ID to use for the multipath device nodes. You must use the numeric group ID. The default value is determined by the process. |