NFS Performance Tuning for HP-UX 11.0 and 11i Systems

nfs performance tuning for hp-ux 11.0 and 11i systems page 112

Notes:

Page 112July 22, 2002

buffer

cache

How much memory should you

configure for buffer cache?

• Sizing too small on clients and servers can result in sub-

optimal performance

• Sizing too large on 11.0 clients can lead to horrendous

NFS performance

• Your mileage will vary, so test with different amounts

Recommended Initial Buffer Cache Sizes

Ø NFS Clients – 400MB or 25% of memory (whichever is LESS)

Ø NFS Servers – 1GB or 50% of memory (whichever is LESS)

Once you’ve decided whether to use static or dynamic buffer cache (based on the

requirements of your applications and environment), the question becomes how

much memory to assign to buffer cache.

As stated earlier, configuring a large buffer cache on 11.0 clients can result in very

poor NFS performance. Although the changes made to the buffer cache code in

11i should allow you to use a larger buffer cache without paying the performance

penalties seen on 11.0, the question is ‘Should you?’ This question can only be

accurately answered through sufficient testing in your own environment, using your

own applications.

There is no one right answer for every NFS client, however a good starting point

for most clients is 400MB or 25% of physical memory – whichever is LESS.

Similarly, there is no one right answer for every NFS server, but a good starting

point for most servers is 1GB or 50% of physical memory – whichever is LESS.