Novell LINUX ENTERPRISE SERVER 11 - STORAGE ADMINISTRATION GUIDE 2-23-2010, Administration Manual, Page: 66 / 140

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Configuring for Round-Robin Load Balancing
All paths are active. I/O is configured for some number of seconds or some number of I/O
transactions before moving to the next open path in the sequence.
Configuring for Single Path Failover
A single path with the highest priority (lowest value setting) is active for traffic. Other paths are
available for failover, but are not used unless failover occurs.
Grouping I/O Paths for Round-Robin Load Balancing
Multiple paths with the same priority fall into the active group. When all paths in that group fail, the
device fails over to the next highest priority group. All paths in the group share the traffic load in a
round-robin load balancing fashion.
rr_min_io Specifies the number of I/O
transactions to route to a path
before switching to the next
path in the same path group,
as determined by the
specified algorithm in the
path_selector setting.
n (>0): Specify an integer value greater than 0.
1000: Default.
rr_weight Specifies the weighting
method to use for paths. uniform: Default. All paths have the same
round-robin weightings.
priorities: Each path’s weighting is determined
by the path’s priority times the rr_min_io setting.
no_path_retry Specifies the behaviors to use
on path failure. n (> 0): Specifies the number of retries until
multipath stops the queuing and fails the path.
Specify an integer value greater than 0.
fail: Specified immediate failure (no queuing).
queue : Never stop queuing (queue forever until
the path comes alive).
failback Specifies whether to monitor
the failed path recovery, and
indicates the timing for group
failback after failed paths
return to service.
When the failed path
recovers, the path is added
back into the multipath
enabled path list based on
this setting. Multipath
evaluates the priority groups,
and changes the active
priority group when the
priority of the primary path
exceeds the secondary
group.
immediate: When a path recovers, enable the
path immediately.
n (> 0): When the path recovers, wait n seconds
before enabling the path. Specify an integer
value greater than 0.
manual: (Default) The failed path is not
monitored for recovery. The administrator runs
the
multipath command to update enabled
paths and priority groups.
Multipath Attribute Description Values