Red Hat DEVICE-MAPPER MULTIPATH 4.6 Configuration And Administration Manual page 34

Chapter 4. The DM-Multipath Configuration File
Attribute
features
hardware_handler
rr_min_io
rr_weight
no_path_retry
Table 4.3. Device Attributes
The following example shows a
# }
# device {
# vendor
# product
# path_grouping_policy multibus
24
Description
A numeric value greater than zero specifies deferred failback,
expressed in seconds.
A value of specifies that failback can happen only with
manual
operator intervention.
The extra features of multipath devices. The only existing
feature is
queue_if_no_path
to
no_path_retry queue
Specifies a module that will be used to perform hardware
specific actions when switching path groups or handling I/O
errors. Possible values include
default value is .
0
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.
If set to , then instead of sending
priorities
requests to a path before calling
path, the number of requests to send is determined by
times the path's priority, as determined by the
rr_min_io
program. Currently, there are priority callouts
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 , all path weights are equal. The default value
uniform
is .
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 indicates immediate failure, without queuing.
fail
A value of indicates that queuing should not stop until
queue
the path is fixed.
The default value is (null).
entry in the multipath configuration file.
device
"COMPAQ
"MSA1000
, which is the same as setting
.
, , and
0 1 emc
selector
group_by_prio
"
"
. The
1 rdac
rr_min_io
to choose the next
path grouping