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

Administering a System: Managing Printers, Software, and Performance
Managing System Performance
Chapter 7 727
Disk Bottlenecks: • high disk activity
• high idle CPU time waiting for I/O requests to finish
• long disk queues
NOTE Put your most frequently accessed information on your fastest disks,
and distribute the workload evenly among identical, mounted disks
so as to prevent overload on a disk while another is under-utilized.
This can often be accomplished by moving swap areas and heavily
accessed file systems off the root disk, or by using disk striping, LVM,
and/or disk mirroring to spread I/Os over multiple disks. See also
“Checking Disk Load with sar and iostat” on page 729.
Network
Bottlenecks:
• Excessive demand on an NFS server.
• LAN bandwidth limitations
Guidelines
Performance is a notoriously difficult topic on which to provide definite
advice; these guidelines should not be taken as formal recommendations
from HP, but merely as the closest the authors could come to distilling a
consensus from the observations of the experts they consulted.
• Keep NFS servers and their clients on the same LAN segment or
subnet. If this is not practical, and you have control over the network
hardware, use switches, rather than hubs, bridges and routers, to
connect the workgroup.
• As far as possible, dedicate a given server to one type of task.
For example, in our sample network (see “A Sample Workgroup /
Network” on page 67) flserver acts as a file server, exporting
directories to the workstations, whereas appserver is running
applications.
If the workgroup needed a web server, it would be wise to configure it
on a third, high-powered system that was not doing other heavy
work.
• On file servers, use your fastest disks for the exported file systems,
and for swap.