Dell MD3620F, MD3600f owner manual Important Information About Special Partitions, 217

Important Information About Special Partitions

When using Device Mapper with the MD3600f Series array, all physical disks are assigned a disk device node. This includes a special device type used for in-band management of the MD3600f Series array, known as the Access Disk or Universal Xport device.

CAUTION: Certain commands, such as lsscsi, displays one or more instances of Universal Xport devices. These device nodes must never be accessed, mounted, or used in any way. Doing so could cause loss of communication to the storage array and possibly cause serious damage to the storage array, potential making data stored on the array inaccessible.

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. 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
<multipath_dev_node>	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's
	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.

Configuration: Device Mapper Multipath for Linux

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