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1 | ==================================== |
2 | Kernel client troubleshooting (FS) | |
3 | ==================================== | |
4 | ||
5 | If there is an issue with the cephfs kernel client, the most important thing is | |
6 | figuring out whether the problem is with the client or the MDS. Generally, | |
7 | this is easy to work out. If the kernel client broke directly, there | |
8 | will be output in dmesg. Collect it and any appropriate kernel state. If | |
9 | the problem is with the MDS, there will be hung requests that the client | |
11fdf7f2 | 10 | 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 |
7c673cae FG |
11 | MDS has probably "forgotten" it. |
12 | We can get hints about what's going on by dumping the MDS cache: | |
13 | ceph mds tell 0 dumpcache /tmp/dump.txt | |
14 | ||
15 | And if high logging levels are set on the MDS, that will almost certainly | |
16 | hold the information we need to diagnose and solve the issue. | |
11fdf7f2 TL |
17 | |
18 | You can also enable dynamic debug against the cephfs module. | |
19 | ||
20 | See: | |
21 | https://github.com/ceph/ceph/blob/master/src/script/kcon_all.sh |