HP-UX System Administrator's Guide: Routine Management Tasks

• Enable asynchronous writes on shared file systems.
See “Checking for Asynchronous Writes” (page 195).
• Make sure enough nfsd daemons are running on the servers.
As a rule, the number of nfsds running should be twice the number of disk
spindles available to NFS clients.
For example, if a server is sharing one file system, and it resides on a volume group
comprising three disks, you should probably be running six nfsds on the server.
For more detail, see “Checking for Socket Overflows with netstat -s” (page 196)
and “Increasing the Number of nfsd Daemons” (page 197).
• Make sure servers have ample memory.
Efforts to optimize disk performance will be wasted if the server has insufficient
memory.
Monitor server memory frequently (see “Measuring Memory Usage with vmstat”
(page 196); and never prepare a hardware budget that doesn’t include additional
memory!
• Defragment servers’ JFS file systems regularly.
Fragmentation means that files are scattered haphazardly across a disk or disks,
the result of growth over time. Multiple disk-head movements are needed to read
and update such files, theoretically slowing response time.
In practice, though, a server is dealing with many I/O requests at a time, and
intelligence is designed into the drivers to take account of the current head location
and direction when deciding on the next seek.
This means that defragmenting an HFS file system on HP-UX may never be
necessary; JFS file systems, however, do need to be defragmented regularly.
See “Defragmenting an HFS File System” (page 198) and “To defragment a JFS file
system using fsadm ” (page 199).
• Keep shared files and directories as small as possible.
Large files require more NFS operations than small ones, and large directories take
longer to search.
Encourage your users to weed out large, unnecessary files regularly (see “Finding
Large Files” (page 153)).
• Monitor server and client performance regularly.
See “Measuring Performance” (page 194).
Resource Hogs
To get an idea of your top CPU hogs, run HP SMH and select Home, Operating System,
Process Information. (Or run /usr/bin/top from the command line.)
Guidelines 193