HP StorageWorks Device Mapper Multipath Enablement Kit for HP StorageWorks Disk Arrays installation and reference guide (AA-RW8RE-TE, June 2009)

Supported ValuesDescriptionAttribute
“round-robin 0”
“least-pending 0”
“service-time 0”
Used to select the path selector
algorithm to be used for mpath.
These algorithms are offered by the
kernel mpath target
path_selector
immediate
n > 0 (user assigned values)
manual
Used to manage the time during
path group failback
failback
/bin/true
/sbin/mpath_prio_alua /dev/%n
Executable to obtain a path weight
for a block device. Weights are
summed for each path group to
determine the next path group to
be used in case of path failure
prio_callout
const
alua
Executable to obtain a path weight
for a block device. Weights are
summed for each path group to
determine the next path group to
be used in case of path failure
prio
uniform
priorities
Used to assign weights to the path
rr_weight
100
1000
The number of IOs to route to a
path before switching to the next in
the same path group
rr_min_io
18
fail
queue
(n =18) indicates the number of
retries until queuing is disabled
(queues till n number of polling), fail
indicates immediate failure (no
queuing), or queue indicates never
stop queuing (queue forever till the
path comes alive)
no_path_retry
Setting up Device Mapper Multipath daemon
You can set the Device Mapper Multipath daemon to start at boot time.
For RHEL hosts, complete the following steps to start the multipathd daemon at boot time:
1. Run the following command to check if the daemon is configured to start at boot time:
# chkconfig --list multipathd
2. Run the following commands to start the Device Mapper Multipath daemon:
# chkconfig [--level levels] multipathd on
# chkconfig multipathd
For SLES hosts, complete the following steps to start the multipathd daemon at boot time:
1. Run the following commands to check if the daemon is configured to start at boot time:
# chkconfig --list boot.device-mapper
# chkconfig --list boot.multipath
Configuring DM Multipath14