Veritas Volume Manager 5.0 Administrator's Guide (September 2006)

79Administering disks
Disk devices
■ 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” on page 133 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# format.
■ Fabric disks are named using the fabric_# format.
See “Changing the disk-naming scheme” on page 90 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” on
page 149.
For a description of disk categories, see “Disk categories” on page 82.
Private and public disk regions
Most VM disks have two regions:
private region A small area where configuration information is stored. A disk header
label, configuration records for VxVM objects (such as volumes,
plexes and subdisks), and an intent log for the configuration database
are stored here. The default private region size is 32 megabytes
(except for VxVM boot disk groups where the private region size must
be 1 megabyte), which is large enough to record the details of several
thousand VxVM objects in a disk group.
Under most circumstances, the default private region size should be
sufficient. For administrative purposes, it is usually much simpler to
create more disk groups that contain fewer volumes, or to split large
disk groups into several smaller ones (as described in “Splitting disk
groups” on page 197). If required, the value for the private region size
may be overridden when you add or replace a disk using the
vxdiskadm command.
Each disk that has a private region holds an entire copy of the
configuration database for the disk group. The size of the
configuration database for a disk group is limited by the size of the