Managing Systems and Workgroups: A Guide for HP-UX System Administrators

Administering a System: Managing Disks and Files
Managing Disks
Chapter 6590
data allocated on three disks, with each disk storing every third block of
data. The size of each of these blocks is referred to as the stripe size of
the logical volume.
Disk striping can increase the performance of applications that read and
write large, sequentially accessed files. Data access is performed over the
multiple disks simultaneously, resulting in a decreased amount of
required time as compared to the same operation on a single disk. If all
of the striped disks have their own controllers, each can process data
simultaneously.
You can use familiar, standard commands to manage your striped disks.
For example, lvcreate (1M), diskinfo (1M), newfs (1M), fsck (1M), and
mount (1M) will all work with striped disks.
The following guidelines, most of which apply to LVM disk usage in
general, apply especially to striped logical volumes for performance
reasons:
• Best performance results from a striped logical volume that spans
similar disks. The more closely you match the striped disks in terms
of speed, capacity, and interface type, the better the performance you
can expect. So, for example, when striping across several disks of
varying speeds, performance will be no faster than that of the slowest
disk.
• If you have more than one interface card or bus to which you can
connect disks, distribute the disks as evenly as possible among them.
That is, each interface card or bus should have roughly the same
number of disks attached to it. You will achieve the best I/O
performance when you use more than one bus and interleave the
stripes of the logical volume. For example, if you have two buses with