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

nfs performance tuning for hp-ux 11.0 and 11i systems page 72

Notes:

Page 72July 22, 2002

Automounter Performance

Considerations (part 2)

• NFS mount options used in master or subordinate maps

Ø Mount options specified in a master map affects all entries of a

subordinate map unless specifically overridden by the map entry

Ø Options such as “noac” or “timeo” can have a dramatic

impact on application performance

automount

autofs

Recommendation

Ø Search all automount maps (local, NIS, NIS+) looking for NFS

mount options and verify the application’s need for using them

Ø Avoid the use of “noac” and “timeo” options whenever possible

Both automount and AutoFS allow NFS mount options to be specified in the map

entries. If these options are included in a filesystem-specific entry within an indirect

or direct map then these options affect only that specific mount point. If the mount

options are specified in a master map entry then these options affect every mount

point within the subordinate direct or indirect map. While modifying the master

map in this manner provides a convenient method of forcing all entries within a

direct/indirect map to use the same mount options, some care should be taken to

ensure that the options specified in the master map are really appropriate for every

underlying NFS mount it affects.

For example, the “–noac” mount option is used to disable client-side attribute

caching for an NFS mount. While this option might be necessary to use on a

specific mount point, it is generally not a good idea to disable attribute caching for

all NFS mounts on a client. In this case, the specific entry within a direct/indirect

map for the mount point that requires the “–noac” option should be modified.

Similarly, the “-timeo” option should be avoided whenever possible. This mount

option, and the reasons to avoid using it, are described in detail on page 98.