How to enable NFS related debug logging
This document (7011571) is provided subject to the disclaimer at the end of this document.
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server 11
SUSE Linux Enterprise Server 10
If you are going to gather debug logs of an NFS issue, here is the approach:
1. Set up the environment so that the problematic behavior can be reproduced immediately. It is best to enable additional debugging when the issue is directly reproduced and no other distracting logs have to be read and analysed. Note, also, that the debug logging can be so intensive and verbose that it may slow down performance of the system. It is not very desirable to leave these debug methods turned on for long periods of time. So the basic steps should be:
a. Enable debugging.
b. Promptly reproduce the issue.
c. Disable debugging.
2. rpcdebug is a command-line tool that enables and disables debugging for various nfs related modules, and various categories of debug logging within those modules. The "-m" flag identifies the module were debug is being activated, and the "-s" option identifies which debug flags will be set.
To generate debug logs for NFS Server functions:
rpcdebug -m nfsd -s all
To generate debug logs for NFS Client functions:
rpcdebug -m nfs -s all
[Note that the difference between nfs server and nfs client is "nfsd" vs "nfs" respectively.]
In many cases the RPC protocol needs to be debugged as well, and that can be achieved by using:
rpcdebug -m rpc -s all
The additional logging information will appear in /var/log/messages or can be viewed with the command "dmesg".
To disable the respective debugging options, use the same command but with the "-c" option to clear the flags in question.
rpcdebug -m nfsd -c all
rpcdebug -m nfs -c all
rpcdebug -m rpc -c all
In cases where you are pretty sure about where the issue resides (nfs server vs nfs client) you may not need to enable debugging at both ends. But in some cases, it may be beneficial to enable rpc/nfs at the NFS client system, and rpc/nfsd at the NFS Server system.
3. Alternative methods:
On some quite old Linux distributions, the "rpcdebug" command does not exist. However, that command is really just a convenient front end to setting values in:
Even without an "rpcdebug" command, you can accomplish the same thing with the sysctl command, or with the echo command.
For example, the sysctl version of the above 3 commands would be:
sysctl -w sunrpc.nfsd_debug=0x7fff
sysctl -w sunrpc.nfs_debug=0xffff
sysctl -w sunrpc.rpc_debug=0x7fff
And setting any of those to 0 or 0x0 would turn that module's debug off again.
Or the echo versions would be:
echo 0x7fff > /proc/sys/sunrpc/nfsd_debug
echo 0xffff > /proc/sys/sunrpc/nfs_debug
echo 0x7fff > /proc/sys/sunrpc/rpc_debug
And echoing 0 or 0x0 into those locations would turn them off again.
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- Document ID:7011571
- Creation Date: 03-Jan-2013
- Modified Date:15-Jul-2020
- SUSE Linux Enterprise Desktop
- SUSE Linux Enterprise Server
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