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

2.2.3.1 Swap Logical Volume Guidelines
Use the following guidelines when configuring swap logical volumes:
• Interleave device swap areas for better performance.
Two swap areas on different disks perform better than one swap area with the equivalent
amount of space. This configuration allows interleaved swapping, which means the swap
areas are written to concurrently, thus enhancing performance.
When using LVM, set up secondary swap areas within logical volumes that are on different
disks using lvextend.
If you have only one disk and must increase swap space, try to move the primary swap area
to a larger region.
• Similar-sized device swap areas work best.
Device swap areas must have similar sizes for best performance. Otherwise, when all space
in the smaller device swap area is used, only the larger swap area is available, making
interleaving impossible.
• By default, primary swap is located on the same disk as the root file system. By default, the
/stand/system system kernel configuration file contains the configuration information for
primary swap.
• If you are using logical volumes as secondary swap, allocate the secondary swap to reside
on a disk other than the root disk for better performance.
2.2.4 Setting Up Logical Volumes for Dump
NOTE: Version 2.0 and 2.1 volume groups do not support configuration of dump logical volume
through lvlnboot(1M) command. However they do support configuring of dump logical volume
through crashconf(1M) command. Please refer the section “Administering dump Logical Volumes
on non-root VGs” (page 107)
This section explains what to consider when using logical volumes as dump devices. A dump area
is disk space used to write an image of the core memory after a system crash. The analysis of a
core dump can be useful in troubleshooting and restoring the system to working order.
By default, the primary swap device also serves as a dump area when no dump area is specifically
designated. Although you are not required to retain primary swap as your dump area, doing so
conserves disk space. You can configure a different or multiple dump devices on your system. To
do this, create a logical volume as a dump device. This device can also be used for swap.
For information on adding, removing, or modifying dump devices, and configuring the dump
algorithms, see the HP-UX System Administrator's Guide: Configuration Management.
2.2.4.1 Dump Logical Volume Guidelines
Use the following guidelines when configuring dump logical volumes:
• HP recommends using logical volumes for dump area rather than disk partitions.
• You can use any secondary swap logical volume as a dump area too, provided the swap
area is in the root volume group.
2.2.5 Setting Up Snapshot Logical Volumes for Backup
Beginning with HP-UX 11i v3 March 2010 Update, LVM introduces snapshot logical volumes,
which can be used to capture point-in-time images of logical volumes quickly and without requiring
as much space as the size of the logical volume. To back up a logical volume while it is in use, a
snapshot of the logical volume can be taken and used for backup while the original logical volume
remains online and is being modified. The snapshot can be deleted after the backup. The approach,
26 Configuring LVM