Red Hat ENTERPRISE LINUX 5.1 DM MULTIPATH, Руководство по настройке и администрированию

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Multipaths Device Configuration Attributes
17
Attribute Description
path_selector
Specifies the default algorithm to use in determining what path to
use for the next I/O operation.
failback
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.
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.
If set to
uniform
, all path weights are equal.
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.
A value of
fail
indicates immediate failure, without queueing.
A value of
queue
indicates that queuing should not stop until the
path is fixed.
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.
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 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 {