Red Hat ENTERPRISE LINUX 5.1 DM MULTIPATH Configuration And Administration Manual page 27

Attribute
path_selector
failback
rr_weight
no_path_retry
rr_min_io
Table 4.2. Multipath Attributes
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
alias
path_grouping_policy
path_checker
path_selector
failback
rr_weight
no_path_retry
}
multipath {
Description
Specifies the default algorithm to use in determining what path to
use for the next I/O operation.
Specifies path group failback.
A value of 0 or immediate specifies that as soon as there is a
path group whith a higher priority than the current path group the
system switches to that path group.
A numeric value greater than zero specifies deferred failback,
expressed in seconds.
A value of manual specifies that failback can happen only with
operator intervention.
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.
If set to uniform, all path weights are equal.
A numeric value for this attribute specifies the number of times
the system should attempt to use a failed path before disabling
queueing.
A value of fail indicates immediate failure, without queueing.
A value of queue indicates that queuing should not stop until the
path is fixed.
Specifies the number of I/O requests to route to a path before
switching to the next path in the current path group.
3600508b4000156d70001200000b0000
yellow
multibus
readsector0
"round-robin 0"
manual
priorities
5
Multipaths Device Configuration Attributes
17