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

nfs performance tuning for hp-ux 11.0 and 11i systems page 73

Notes:

Page 73July 22, 2002

Automounter Performance

Considerations (part 3)

• Replicated NFS Servers in Maps

Ø Ensure the specified servers exist, respond quickly to mount

requests, and contain the filesystem referenced in the map

• Environment Variables in Maps (“-D” option)

Ø Ensure the pathnames resolved by variables exist on the server

• Hierarchical Maps

Ø Entire hierarchy must be mounted/unmounted together

Ø Adds overhead both to client’s automounter and server’s

rpc.mountd when only a portion of the hierarchy is used

automount

autofs

Both automount and AutoFS allow the administrator to configure multiple replicated

NFS servers for a given mount point. If you plan to use this feature be certain to

only list NFS servers that truly exist, are responding to mount requests quickly, and

contain the filesystem referenced in the map. Otherwise the automounter will waste

cycles looking for servers that don’t exist, are down, or don’t contain the data they

need to satisfy the mount request.

Both automounters provide the ability to specify environment variables via the “–D”

option and then reference those variables in the maps. This feature also requires a

good deal of planning and coordination to ensure that the pathnames resolved via

these environment variables actually exist on the target NFS servers.

Automount and AutoFS will attempt to unmount filesystems that are not in use every

5 minutes (default). While this value can add some overhead to the client system

by having automounter attempt to unmount filesystems frequently, it can also add a

substantial amount of load to the NFS server’s rpc.mountd daemon – particularly

when hierarchical maps are used, since automount attempts to unmount the entire

hierarchy and must re-mount it if any part of the hierarchy is busy.