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Disk device naming in VxVM

Prior to VxVM 3.2, all disks were named according to the c#t#d#s# naming format used by the operating system. Fabric mode disks were not supported by VxVM. From VxVM 3.2 onward, there are two different methods of naming disk devices:

• c#t#d#s# based naming
• Enclosure based naming

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    Note   Disk devices controlled by MPXIO are always in fabric mode (irrespective of their hardware configuration), and are therefore named in the enclosure name format. This is true for both naming schemes.

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c#t#d#s# based naming

In this naming scheme, all disk devices except fabric mode disks are named using the c#t#d#s# format.

The syntax of a device name is c#t#d#s#, where c# represents a controller on a host bus adapter, t# is the target controller ID, d# identifies a disk on the target controller, and s# represents a partition (or slice) on the disk.

  Note   For non-EFI disks, the slice s2 represents the entire disk. For both EFI and non-EFI disks, the entire disk is implied if the slice is omitted from the device name.

The boot disk (which contains the root file system and is used when booting the system) is often identified to VxVM by the device name c0t0d0.

Fabric mode disk devices are named as follows:

• Disk in supported disk arrays are named using the enclosure name_# format. For example, disks in the supported disk array name FirstFloor are named FirstFloor_0, FirstFloor_1, FirstFloor_2 and so on. (You can use the vxdmpadm command to administer enclosure names.)
• Disks in the DISKS category (JBOD disks) are named using the Disk_# format.
• Disks in the OTHER_DISKS category (disks that are not multipathed by DMP) are named using the fabric_# format.

Enclosure based naming

Enclosure-based naming operates as follows:

• Devices with very long device names (for example, Fibre Channel devices that include worldwide name (WWN) identifiers) are always represented by enclosure-based names.
• All fabric or non-fabric disks in supported disk arrays are named using the enclosure_name_# format. For example, disks in the supported disk array, enggdept are named enggdept_0, enggdept_1, enggdept_2 and so on. (You can use the vxdmpadm command to administer enclosure names. See Administering DMP using vxdmpadm and the vxdmpadm(1M) manual page for more information.)
• Disks in the DISKS category (JBOD disks) are named using the Disk_# format.
• Disks in the OTHER_DISKS category (disks that are not multipathed by DMP) are named as follows:
  • Non-fabric disks are named using the c#t#d#s# format.
  • Fabric disks are named using the fabric_# format.

See Changing the disk-naming scheme for details of how to switch between the two naming schemes.

To display the native OS device names of a VM disk (such as mydg01), use the following command:

# vxdisk path | egrep diskname

For information on how to rename an enclosure, see Renaming an enclosure.

For a description of disk categories, see Disk categories.