Installation guide

dd l n nnn p
The elements in the disk access name are described in the following
table:
Element Description
dd
A two-character device mnemonic that shows the disk type. Use
ra for DSA disks and rz for SCSI disks.
[l]
The SCSI logical unit number (LUN), in the range from a to h, to
correspond to LUNs 0 through 7. This argument is optional and
used for SCSI Redundant Arrays of Independent Disks (RAID)
devices.
n[nnn]
The disk unit number ranging from 1 to 4 digits.
[p]
The partition letter, in the range from a to h, to correspond to
partitions 0 through 7. This argument is optional.
For example, rz in the device name rz3 represents a pseudonym for a
SCSI disk, and rzb10h (LUN 1) represents a disk access name for a
Digital SCSI RAID device having a LUN of one and using partition h.
For an LSM simple disk or an LSM nopriv disk, you must specify a
partition letter (for example, rz3d). For an LSM sliced disk, you must
specify a physical drive that does not have a partition letter (for
example, rz3). The proper full pathname of the d partition on this
simple device is /dev/rz3d. For easier reading, this document often
lists only the disk access name and /dev is assumed. Also, note that
you do not specify /dev in front of the device name when using LSM
commands.
• Disk media name (also referred to as the disk name)
An administrative name for the disk, such as disk01. If you do not
assign a disk media name, it defaults to disk
nn , where nn is a
sequence number if the disk is being added to rootdg. Otherwise, the
default disk media name is groupname
nn , where groupname
represents the name of the disk group to which the disk is added.
8.2.4 LSM Disk Groups
You can organize a collection of physical disks that share a common
configuration or function into disk groups. LSM volumes are created within
a disk group and are restricted to using disks within that disk group.
Use disk groups to simplify management and provide data availability. For
example:
• On a system with a large number of disks, you might want to divide
disk usage into a few disk groups based on function. This would reduce
8–8 Administering the Logical Storage Manager