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1 print the multipath names only
2 print all info
3 print debug information
-p policy
force all maps to specified path_grouping_policy
failover 1 path per priority group
multibus all paths in 1 priority group
group_by_serial 1 priority group per serial
group_by_prio 1 priority group per priority level
group_by_node_name 1 priority group per target node
device
limit scope to the device's multipath (udev-style DEVNAME
reference, eg /dev/sdb or major:minor or a device map name)
Here is an example of how to create a multipath device and change the MPIO policy
between failover and round-robin.
# multipath -F // Clear existing device-
// maps
# multipath // Create devicemaps
create: mpath4 (320a6001378a8a27a) Qsan,P150C
[size=100G][features=0][hwhandler=0]
\_ round-robin 0 [prio=1][undef]
\_ 2:0:0:0 sdb 8:16 [undef][ready]
\_ round-robin 0 [prio=1][undef]
\_ 3:0:0:0 sdc 8:32 [undef][ready]
# fdisk -l
Disk /dev/sdb: 107.3 GB, 107374182400 bytes
255 heads, 63 sectors/track, 13054 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk /dev/sdb doesn't contain a valid partition table
Disk /dev/sdc: 107.3 GB, 107374182400 bytes
255 heads, 63 sectors/track, 13054 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk /dev/sdc doesn't contain a valid partition table
Disk /dev/dm-2: 107.3 GB, 107374182400 bytes // abstract device maps to
255 heads, 63 sectors/track, 13054 cylinders // /dev/sdb and /dev/sdc
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk /dev/dm-2 doesn't contain a valid partition table
# multipath -l // List the multipath
mpath4 (320a6001378a8a27a) dm-2 Qsan,P150C // topology, default MPIO
[size=100G][features=0][hwhandler=0] // policy is failover
\_ round-robin 0 [prio=0][active]
\_ 2:0:0:0 sdb 8:16 [active][undef]
\_ round-robin 0 [prio=0][enabled]
\_ 3:0:0:0 sdc 8:32 [active][undef]
# multipath -p multibus mpath4 // Change the MPIO policy
reload: mpath4 (320a6001378a8a27a) Qsan,P150C // to multibus (round-
[size=100G][features=0][hwhandler=0] // robin)
\_ round-robin 0 [prio=2][undef]
\_ 2:0:0:0 sdb 8:16 [active][ready]
\_ 3:0:0:0 sdc 8:32 [active][ready]
# multipath -p failover mpath4 // Change the MPIO policy
reload: mpath4 (320a6001378a8a27a) Qsan,P150C // to failover
[size=100G][features=0][hwhandler=0]
\_ round-robin 0 [prio=1][undef]
\_ 2:0:0:0 sdb 8:16 [active][ready]
\_ round-robin 0 [prio=1][undef]
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