NFS Services Administrator Guide for 11i v3 (5900-2572, September 2012)

□ If the value of getattr displayed by nfsstat -s is greater than 60%, one or more clients
have either turned off attribute caching (with the noac mount option) or set the caching timeout
values too low.
Increase the attribute caching timeouts on the clients that have them set below the default
values. See “Changing the Default Mount Options” (page 38)“Changing the Default Mount
Options” on page 51.
□ Share directories with the async option. When async is specified, the server acknowledges
write requests from clients before writing data to a disk. Clients do not have to wait for a write
request to complete before issuing another request. This can be performed only for NFSv2.
The default option for NFSv3 is async.
Improving NFS Client Performance
□ For files and directories that are mounted read-only and never change, set the actimeo mount
option to 120 or greater in the /etc/fstab file on your NFS clients.
□ If you see several “server not responding” messages within a few minutes, try doubling
the value of the timeo mount option in the /etc/fstab file on your NFS clients.
□ If you frequently see the following message when attempting access to a soft-mounted directory,
NFS operation failed for server servername: Timed out
try increasing the value of the retrans mount option in the /etc/fstab file on the NFS
clients. Or, change the soft mount to an interruptible hard mount, by specifying the hard and
intr options (the defaults).
□ Enter the following command on the NFS server, to find out the block size of the server’s
filesystem:
/usr/sbin/tunefs -v devicefilename
On the NFS clients, set the wsize and rsize mount options to the bsize value displayed
by tunefs.
□ On the NFS clients, look in the /etc/fstab file for “stepping-stone” mounts (hierarchical
mounts), as in the following example:
thyme:/usr /usr nfs defaults 0 0
basil:/usr/share /usr/share nfs defaults 0 0
sage:/usr/share/lib /usr/share/lib nfs defaults 0 0
Wherever possible, change these “stepping-stone” mounts so that whole directories are
mounted from a single NFS server.
Stepping-stone (hierarchical) mounts, like the one in the example above, cause more NFS
requests than mounts from a single server. In the example, if a client wants access to something
in /usr/share/lib, a request must be sent to server thyme, then to server basil, and
finally to server sage.
For more information on the stepping-stone mounts, see “Changing the Default Mount Options”
(page 38).
Logging and Tracing of NFS Services
This section tells you how to start the following tools:
• “AutoFS Logging” (page 74)
• “AutoFS Tracing” (page 75)
• “Logging for the Other NFS Services” (page 101)
100 Troubleshooting NFS Services