Red Hat CLUSTER SUITE 4.7 DM MULTIPATH Configuration And Administration Manual page 29

Attribute
hardware_handler
rr_min_io
rr_weight
no_path_retry
Table 4.3. Device Attributes
The following example shows a device entry in the multipath configuration file.
# }
# device {
# vendor "COMPAQ
# product "MSA1000
# path_grouping_policy multibus
# path_checker
# rr_weight priorities
# }
#}
Description
Specifies a module that will be used to perform hardware specific
actions when switching path groups or handling I/O errors.
Possible values include 0, 1 emc, and 1 rdac. The 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 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. The default value 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 fail indicates immediate failure, without queuing.
A value of queue indicates that queuing should not stop until the
path is fixed.
The default value is (null).
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Configuration File Devices
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