Only multipathing device nodes and partition nodes created using the
directions provided above should be mounted or in any way accessed by the
host system or its users.
Table 14-1. Useful Device Mapper Commands
Command
multipath –h
multipath –ll
multipath
multipath –f
<multipath_dev_node>
multipath –F
rescan_dm_devs
Limitations and Known Issues
•
In certain error conditions with the no_path_retry or the
queue_if_no_path feature is set, applications may hang. To overcome
these conditions the you must enter the following command for each
affected multipath device:
dmsetup message [device] 0 "fail_if_no_path"
where [device] is the multipath device name (e.g. mpath2; do not specify
the path)
184
Configuration: Device Mapper Multipath for Linux
Descriptions
Prints usage information
Displays the current multipath topology using all available
information (sysfs, the device mapper, path checkers, and
so on)
Re-aggregates multipathing device with simplified output.
Flushes out Device Mapper for the specified multipathing
device. Used if the underlying physical devices are
deleted/unmapped.
Flushes out all unused multipathing device maps.
Dell provided script. Forces a rescan of the host SCSI bus
and aggregates multipathing devices as needed. For use
when:
• LUNs are dynamically mapped to the hosts.
• New targets are added to the host.
• Failback of the storage array is required.
• For MD3200i Series arrays, iSCSI sessions have to be
established for rescan to take effect.