From: Greg Farnum Date: Mon, 19 Mar 2012 20:20:40 +0000 (-0700) Subject: doc: add a short thing on kernel client troubleshooting. X-Git-Tag: v0.45~46^2~1^2~3 X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=d0ba27ae50c0edd21bebb8b8b4ad1623567090a4;p=ceph.git doc: add a short thing on kernel client troubleshooting. I just noticed this sitting uncommitted in my tree. Signed-off-by: Greg Farnum --- diff --git a/doc/dev/kernel-client-troubleshooting.rst b/doc/dev/kernel-client-troubleshooting.rst new file mode 100644 index 000000000000..03ba067eba04 --- /dev/null +++ b/doc/dev/kernel-client-troubleshooting.rst @@ -0,0 +1,17 @@ +============ + Kernel client troubleshooting (FS) +============ + +If there is an issue with the cephfs kernel client, the most important thing is +figuring out whether the problem is with the client or the MDS. Generally, +this is easy to work out. If the kernel client broke directly, there +will be output in dmesg. Collect it and any appropriate kernel state. If +the problem is with the MDS, there will be hung requests that the client +is waiting on. Look in /sys/kernel/debug/ceph/*/ and cat the mdsc file to +get a listing of requests in progress. If one of them remains there, the +MDS has probably "forgotten" it. +We can get hints about what's going on by dumping the MDS cache: +ceph mds tell 0 dumpcache /tmp/dump.txt + +And if high logging levels are set on the MDS, that will almost certainly +hold the information we need to diagnose and solve the issue.