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18 lines
855 B
ReStructuredText
18 lines
855 B
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============
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Kernel client troubleshooting (FS)
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============
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If there is an issue with the cephfs kernel client, the most important thing is
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figuring out whether the problem is with the client or the MDS. Generally,
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this is easy to work out. If the kernel client broke directly, there
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will be output in dmesg. Collect it and any appropriate kernel state. If
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the problem is with the MDS, there will be hung requests that the client
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is waiting on. Look in /sys/kernel/debug/ceph/*/ and cat the mdsc file to
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get a listing of requests in progress. If one of them remains there, the
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MDS has probably "forgotten" it.
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We can get hints about what's going on by dumping the MDS cache:
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ceph mds tell 0 dumpcache /tmp/dump.txt
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And if high logging levels are set on the MDS, that will almost certainly
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hold the information we need to diagnose and solve the issue.
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