Red Hat DEVICE-MAPPER MULTIPATH 4.6 Configuration And Administration Manual page 31

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
The second multipath device in the example has a WWID of
symbolic name of
red
Description
group_by_serial
number
group_by_prio
group_by_node_name
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
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
operator intervention.
If set to
priorities
requests to a path before calling
path, the number of requests to send is determined by
rr_min_io
prio_callout
only for devices that use the
policy, which means that all the paths in a path group will
always have the same priority.
If set to
uniform
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
A value of
queue
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.
and a symbolic name of
. In this example, the
rr_weight
Multipaths Device Configuration Attributes
= 1 priority group per detected serial
= 1 priority group per path priority value
= 1 priority group per target node name
specifies that as soon as there is a
immediate
specifies that failback can happen only with
, then instead of sending
selector
times the path's priority, as determined by the
program. Currently, there are priority callouts
group_by_prio
, all path weights are equal.
indicates immediate failure, without queueing.
indicates that queuing should not stop until
yellow
1DEC_____321816758474
attributes is set to
rr_min_io
to choose the next
path grouping
.
and a
.
priorities
21