Dell PowerVault MD3220i Owner's Manual - Page 184

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 Descriptions multipath -h Prints usage information multipath -ll Displays the current multipath topology using all available information (sysfs, the device mapper, path checkers, and so on) multipath Re-aggregates multipathing device with simplified output. multipath -f Flushes out Device Mapper for the specified multipathing device. Used if the underlying physical devices are deleted/unmapped. multipath -F Flushes out all unused multipathing device maps. rescan_dm_devs 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. 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