File System Logical Volume Guidelines; Setting Up Logical Volumes For Swap; Swap Logical Volume Guidelines - HP -UX 11i Administrator's Manual

TIP: Because increasing the size of a file system is usually easier than reducing its size, be
conservative in estimating how large to create a file system.
An exception is the root file system. As a contiguous logical volume, the root file system is difficult
to extend.
Resizing File System Logical Volumes
If your users have outgrown the space originally allocated for the file system, you can increase its
size by first enlarging the logical volume it resides in using the lvextend command, then using
the extendfs command to enlarge the file system contained in the logical volume.
Decreasing the size of a file system can be difficult. Based on the type of file system, you might
not be able to decrease its size. However, you can create a new smaller file system to take its
place.
For more information on resizing file system logical volumes, see
Volumes" (page

File System Logical Volume Guidelines

Use the following guidelines when configuring file system logical volumes:
If you create a file system that spans LVM disks, be sure that the logical volume in which the
file system resides spans identical disk types for best system performance.
By default, LVM creates logical volumes on available disks, not necessarily with regard for
best performance. A file system can span two disks with different characteristics, in which
case the file system performance can possibly be impaired.
You can control which physical volumes contain the physical extents of a logical volume by
following these steps:
1. Create a logical volume without specifying a size using the lvcreate command or HP
SMH. When you do not specify a size, by default, no physical extents are allocated for
the logical volume.
2. Extend the logical volume (that is, allocate space) to the specific physical volumes you
want to contain the file system using the lvextend command.
The root or boot logical volume is limited to either 2 GB or 4 GB, depending on your processor.

Setting Up Logical Volumes for Swap

NOTE: Version 2.0 and 2.1 volume groups do not support swap logical volumes.
This section explains what to consider when using logical volumes as swap devices. For information
on managing your system swap space, including determining how much and what type of swap
space the system needs, see HP-UX System Administrator's Guide: Configuration Management.
When configured as swap, logical volumes are treated as device swap space. Device swap space
occupies a logical volume or partition, which is typically reserved expressly for swapping purposes.
This space can also be configured as a dump area (See
(page 23)).

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.
22 Configuring LVM
97).
"Administering File System Logical
"Dump Logical Volume Guidelines"