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4.4. Multipaths Device Configuration Attributes
Table 4.2, “Multipath Attributes” shows the attributes that you can set in the
multipaths section of the multipath.conf configuration file for each specific multipath device. These attributes apply only to the one specified multipath. These defaults are used by DM-Multipath and override attributes set in the defaults and devices sections of the multipath.conf file.
| Attribute | Description | |||||
|---|---|---|---|---|---|---|
wwid | Specifies the WWID of the multipath device to which the multipath attributes apply. | |||||
alias | Specifies the symbolic name for the multipath device to which the multipath attributes apply. | |||||
path_grouping_policy | Specifies the default path grouping policy to apply to unspecified multipaths. Possible values include:
| |||||
path_selector | Specifies the default algorithm to use in determining what path to use for the next I/O operation. | |||||
rr_min_io | (RHEL 4.8 and later) Specifies the number of I/O requests to route to a path before switching to the next path in the current path group. | |||||
failback | Specifies path group failback.
| |||||
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. | |||||
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. |
The following example shows multipath attributes specified in the configuration file for two specific multipath devices. The first device has a WWID of
3600508b4000156d70001200000b0000 and a symbolic name of yellow.
The second multipath device in the example has a WWID of
1DEC_____321816758474 and a symbolic name of red. In this example, the rr_weight attributes is set to priorities.
multipaths {
multipath {
wwid 3600508b4000156d70001200000b0000
alias yellow
path_grouping_policy multibus
path_checker readsector0
path_selector "round-robin 0"
failback manual
rr_weight priorities
no_path_retry 5
}
multipath {
wwid 1DEC_____321816758474
alias red
rr_weight priorities
}
}
