HP-UX System Administrator's Guide: Logical Volume Management (762803-001, March 2014)

Version 1.0 is the version supported on all current and previous versions of HP-UX 11i. The
procedures and command syntax for managing Version 1.0 volume groups are unchanged from
previous releases. When creating a new volume group, vgcreate defaults to Version 1.0.
Version 2.0, 2.1, and 2.2 enable the configuration of larger volume groups, logical volumes,
physical volumes, and other parameters. Version 2.1 is identical to Version 2.0, but allows a
greater number of volume groups, physical volumes, and logical volumes. Version 2.x volume
groups are managed exactly like Version 1.0 volume groups, with the following exceptions:
• Version 2.x volume groups have simpler options to the vgcreate command. When creating
a Version 2.x volume group, you specify only the extent size and the maximum size to which
the volume group can grow. This gives LVM greater flexibility in managing space; you can
use the same parameters for a volume group with many small PVs and for a volume group
with a few large PVs. For more information on volume group creation, see “Creating a Volume
Group” (page 47)
• Version 2.0 volume groups are not recognized on previous releases of HP-UX, including
versions of HP-UX 11i Version 3 before March 2008. Version 2.1 volume groups are not
recognized on previous releases of HP-UX, including versions of HP-UX 11i Version 3 before
September 2008. Version 2.2 volume groups are only supported on systems operating with
the HP-UX 11i Version 3 March 2010 Update and forward.
• Version 2.0 and 2.1 volume groups do not support root, boot, swap, or dump logical volumes.
The lvlnboot and lvrmboot commands display an error message if run on a Version 2.0
or 2.1 volume group. Note that Version 2.2 and higher do support root, boot, swap, or dump
logical volumes. However, you can configure logical volumes from version 2.0/2.1 volume
groups as secondary swap or additional dump devices through
swapon(1M)/crashconf(1M) commands respectively. Refer to “Administering Swap
Logical Volumes” (page 104) and “Administering Dump Logical Volumes” (page 106) sections
for further details.
• Version 2.0 and 2.1 volume groups do not support bootable physical volumes. You cannot
add a physical volume created with pvcreate -B to a Version 2.0 or 2.1 volume group.
Note that Version 2.2 and higher do support bootable physical volumes.
• Version 2.2 or higher volume groups support creation of snapshots of logical volumes.
• Version 2.x volume groups do not support disk sparing. Using the -z option to the vgextend
or pvchange command displays an error message.
• The pvck command is not supported on Version 2.x volume groups.
• Some HP-UX products do not support Version 2.x volume groups. For more information, see
the HP-UX Logical Volume Manager and MirrorDisk/UX Release Notes for your release.
To compare Version 1.0 and Version 2.x volume groups, see the tables that list maximum limits
for different volume group versions in “LVM Specifications and Limitations” (page 159). You can
also display volume group limits with the lvmadm command; an example is shown in “LVM
Specifications and Limitations” (page 159) . The lvmadm is fully covered in the lvmadm(1M) manual
page.
See “Creating and Administering Snapshot Logical Volumes” (page 108) for information about
snapshot logical volumes.
1.5 LVM device file usage
All LVM components are represented by device special files located in the /dev directory. Device
special files act as agents for managing the interactions with the disk space. The LVM device files
are created by both HP SMH and HP-UX commands. This section describes the device special files
used by LVM, and naming conventions for LVM objects.
HP-UX 11i v3 introduces a new representation of mass storage devices called the agile view. In
this representation, the device special file (DSF) name for each disk no longer contains path (or
1.5 LVM device file usage 15