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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 # max_fds 8192 # rr_weight priorities # failback immediate # no_path_retry fail # user_friendly_names 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 . | |||||||
verbosity | (Red Hat Enterprise Linux 5.3 and later) Specifies the verbosity level of the command. It can be overridden by the -v command line option. The default value is 2. | |||||||
polling_interval | Specifies the interval between two path checks in seconds. The default value is 5. | |||||||
selector, path_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 . selector and path_selector have the same meaning; the path_selection attribute is supported in Red Hat Enterprise Linux 5.8 and later. | |||||||
path_grouping_policy |
| |||||||
getuid_callout |
| |||||||
prio_callout | Specifies the default program and arguments to call out to obtain a path weight. Weights are summed for each path group to determine the next path group to use in case of failure. "none" is a valid value. This parameter accepts the same wildcard values as getuid_callout . | |||||||
path_checker | Specifies the default method used to determine the state of the paths. Possible values include: readsector0 , rdac , tur , cciss_tur , hp_tur (Red Hat Enterprise Linux 5.5 and later), emc_clariion , hp_sw , and directio . The default value is readsector0 . | |||||||
features |
| |||||||
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 | (Red Hat Enterprise Linux 5.2 and later) Sets the maximum number of open file descriptors for the multipathd process. In Red Hat Enterprise Linux 5.3, this option allows a value of max , which sets the number of open file descriptors to the system maximum. As of the Red Hat Enterprise Linux 5.9 release, the default value is max , which sets this to the system limit from /proc/sys/fs/nr_open . For earlier releases, if this is not set the maximum number of open file descriptors 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 greater than 1024. | |||||||
rr_weight |
| |||||||
failback |
| |||||||
no_path_retry |
| |||||||
flush_on_last_del | (Red Hat Enterprise Linux 5.3 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 . | |||||||
queue_without_daemon | (Red Hat Enterprise Linux 5.3 and later) If set to no , the multipathd daemon will disable queueing for all devices when it is shut down. As of Red Hat Enterprise Linux release 5.9, the default value is no ; for earlier releases, the default value is yes . | |||||||
user_friendly_names | If set to yes , specifies that the system should using the bindings file to assign a persistent and unique alias to the multipath, in the form of mpath n . The default location of the bindings file is /var/lib/multipath/bindings , but this can be changed with the bindings_file option. 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 | (Red Hat Enterprise Linux 5.2 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 | (Red Hat Enterprise Linux 5.3 and later) The mode to use for the multipath device nodes, in octal. The default value is determined by the process. | |||||||
uid | (Red Hat Enterprise Linux 5.3 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 | (Red Hat Enterprise Linux 5.3 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. | |||||||
checker_timeout | (Red Hat Enterprise Linux 5.5 and later) The timeout value to use for path checkers that issue SCSI commands with an explicit timeout, in seconds. The default value is taken from sys/block/sdx/device/timeout . | |||||||
pg_prio_calc | (Red Hat Enterprise Linux 5.6 and later) If set to avg , sets the priority of path groups to the average of the priorities of the included paths. If set to sum , sets the priority of path groups to the sum of the priorities of the included paths. As of Red Hat Enterprise Linux release 5.9, the default value is avg ; for earlier releases, the default value is sum . | |||||||
log_checker_err | (Red Hat Enterprise Linux 5.6 and later) If set to once , a path checker error is logged once at logging level 2 and any later errors are logged at level 3 until the device is restored. If set to always , every path checker error is logged at logging level 2. The default value is always . | |||||||
fast_io_fail_tmo | (Red Hat Enterprise Linux 5.7 and later) The number of seconds the SCSI layer will wait after a problem has been detected on an FC remote port before failing I/O to devices on that remote port. This value should be smaller than the value of dev_loss_tmo . Setting this to off will disable the timeout. The default value is determined by the OS. | |||||||
dev_loss_tmo | (Red Hat Enterprise Linux 5.7 and later) The number of seconds the SCSI layer will wait after a problem has been detected on an FC remote port before removing it from the system. The default value is determined by the OS. | |||||||
file_timeout | (Red Hat Enterprise Linux 5.7 and later) The number of seconds multipath will wait for a necessary file to appear while setting up a multipath device. The default value is 90 . |