Dell PowerVault MD3820f - Manual (Page 197)

In the following command descriptions, <x> is used to indicate where a substitution must be made. On
Red Hat Enterprise Linux systems, <x> is the number assigned to the device. On SUSE Linux Enterprise
Server systems, <x> is the letter(s) assigned to the device.
Scan For Newly Added Virtual Disks
The rescan_dm_devs command scans the host server system looking for existing and newly added
virtual disks mapped to the host server.
# rescan_dm_devs
If an array virtual disk (VD) is mapped to the host server at a later time the rescan_dm_devices
command must be run again to make the VD a visible LUN to the operating system.
Display The Multipath Device Topology Using The Multipath Command
The multipath command adds newly scanned and mapped virtual disks to the Device Mapper tables and
creates entries for them in the/dev/mapper directory on the host server. These devices are the same as
any other block devices in the host.
To list all the multipath devices, run the following command:
# multipath –ll
The output must be similar to this example, which shows the output for one mapped virtual disk.
mpath1 (3600a0b80005ab177000017544a8d6b92) dm-0 DELL, MD3xxxx[size=5.0G]
[features=3 queue_if_no_path pg_init_retries 50][hwhandler=1 rdac][rw]\_ round-
robin 0 [prio=6][active] \_ 5:0:0:0 sdc 8:32 [active][ready]\_ round-robin
0 [prio=1][enabled] \_ 4:0:0:0 sdb 8:16 [active][ghost]
where:
mpath1 is the name of the virtual device created by device mapper. It is located in the /dev/mapper
directory.
DELL is the vendor of the device.
MD3xxxx is the model of the device.
Sdc is the physical path to the owning controller for the device.
Sdb is the physical path to the non-owning controller for the device.
The following is an example of SLES output:
mpathb(360080e500017b2f80000c6ca4a1d4ab8) dm-21 DELL,MD3xxxx[size=1.0G]
[features=3 queue_if_no_path pg_init_retries 50][hwhandler=1 rdac][rw]\_ round-
robin 0 [prio=6][active] \_ 4:0:0:22 sdx 65:112 [active][ready]\_ round-robin
0 [prio=1][enabled] \_ 6:0:0:22 sdcl 69:144 [active][ghost]
where:
mpathb is the name of the virtual device created by device mapper. It is located in the/dev/mapper
directory.
DELL is the vendor of the device.
MD3xxxx is the model of the device.
Sdx is the physical path to the owning controller for the device.
Sdcl is the physical path to the non-owning controller for the device.
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