Common NFS Errors
- "No such host" - Name of the server is specified incorrectly
- "No such file or directory" - Either the local or remote file system is specified incorrectly.
- "No such device" - NFS is not configured into the client's kernel.
- "NFS server is not responding" message followed by "NFS server xxxx OK" - Server is heavily loaded causing RPC timeouts, or server has crashed.
- "Stale file handle" - The file is no longer available.
- "MOUNT_PROG not registered" - rpc.mountd daemon never started up and registered.
- "Too many levels of remote in path" - Attempting to mount a file system which is already an NFS mounted file system.
- "Permission denied" - Accessing as root on the client and root is mapped to nobody. Or the user on the client does not have corresponding UID on the server.
- "No space" - The server is out of space on the file system.
Troubleshooting
The showmount command may be used to display server-side mount information. The option -a displays all remote mounts showing the name of the client and the directory, separated by a colon. The -d option displays only the names of the directories mounted by the clients. And the -e option displays the list of file systems exported by the server. # showmount -a
All mount points on local host:
edcert20.ucs.indiana.edu:/home
edcert21.ucs.indiana.edu:/usr/local
# showmount -d
Directories on local host:
/home
/usr/local
# showmount -e
Export list on local host
/home edcert21.ucs.indiana.edu edcert20.ucs.indiana.edu
/usr/local edcert21.ucs.indiana.edu
The df command may be used to display information on the file
systems mounted remotely, the mount point and the amount of available
space. The -F option may be specified to list only a specified
file system type.
# df -F nfs
Filesystem Type blocks use avail %use Mounted on
edcert21.ucs.indiana.edu:/home nfs 68510 55804 12706 81% /usr/share/help
BSD systems use -t option to specify the fstype. The output from
the df command also varies among the different operating systems.
df also resolves the symbolic links and determines the file system
mounted at the link's target. For example:
# ls -l /usr/local/man
lrwxr-xr-x 1 root sys 6 Mar 17 1995 /usr/local/man -> catman/
# df /usr/local/man
Filesystem Type blocks use avail %use Mounted on
orange:/usr/local nfs 68510 55804 12706 81% /usr/local
Use the command nfsstat -s to display NFS activity on the
server side. For example:
# nfsstat -s
Server RPC:
calls badcalls nullrecv badlen xdrcall duphits dupage
50852 0 0 0 0 0 0.00
Server NFS:
calls badcalls
50852 0
null getattr setattr root lookup readlink
1 0% 233 0% 0 0% 0 0% 1041 2% 0 0%
read wrcache write create remove rename
49498 97% 0 0% 0 0% 0 0% 0 0% 0 0%
link symlink mkdir rmdir readdir fsstat
0 0% 0 0% 0 0% 0 0% 75 0% 4 0%
The output may be interpreted using the following guidelines.
- badcalls > 0 - RPC requests are being rejected by the server. This could indicate authentication problems caused by having a user in too many groups, attempts to access exported file systems as root, or an improper Secure RPC configuration.
- nullrecv > 0 - NFS requests are not arriving fast enough to keep all of the nfsd daemons busy. Reduce the number of NFS server daemons until nullrecv is not incremented.
- symlink > 10% - Clients are making excessive use of symbolic links that are on file systems exported by the server. Replace the symbolic link with a directory, and mount both the underlying file system and the link's target on the client.
- getattr > 60% - Check for non-default attribute caching (noac mount option) on NFS clients.
# nfsstat -c
Client RPC:
calls badcalls retrans badxid timeout wait newcred
369003 62 1998 43 2053 0 0
Client NFS:
calls badcalls nclget nclsleep
368948 0 368948 0
null getattr setattr root lookup readlink
0 0% 51732 14% 680 0% 0 0% 95069 25% 542 0%
read wrcache write create remove rename
210187 56% 0 0% 2259 0% 1117 0% 805 0% 337 0%
link symlink mkdir rmdir readdir fsstat
120 0% 0 0% 7 0% 0 0% 5510 1% 583 0%
This output may be interpreted using the guidelines given below.
- timeout > 5% - The client's RPC requests are timing out before the server can answer them, or the requests are not reaching the server. Check badxid to determine the problem.
- badxid ~ timeout - RPC requests are being handled by the server, but too slowly. Increase timeo parameter value for this mount, or tune the server to reduce the average request service time.
- badxid ~ 0 - With timeouts greater than 3%, this indicates that packets to and from the server are getting lost on the network. Reduce the read and write block sizes (mount parameters rsize and wsize) for this mount.
- badxid > 0 - RPC calls on soft-mounted file systems are timing out. If the server is running, and badcalls is growing, then soft mounted file systems should use a larger timeo or retrans value.
Read More on http://www.cs.bgu.ac.il/~arik/usail/network/nfs/tips.html
