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diff --git a/src/ceph/doc/cephfs/troubleshooting.rst b/src/ceph/doc/cephfs/troubleshooting.rst deleted file mode 100644 index 4158d32..0000000 --- a/src/ceph/doc/cephfs/troubleshooting.rst +++ /dev/null @@ -1,160 +0,0 @@ -================= - Troubleshooting -================= - -Slow/stuck operations -===================== - -If you are experiencing apparent hung operations, the first task is to identify -where the problem is occurring: in the client, the MDS, or the network connecting -them. Start by looking to see if either side has stuck operations -(:ref:`slow_requests`, below), and narrow it down from there. - -RADOS Health -============ - -If part of the CephFS metadata or data pools is unavaible and CephFS is not -responding, it is probably because RADOS itself is unhealthy. Resolve those -problems first (:doc:`../../rados/troubleshooting/index`). - -The MDS -======= - -If an operation is hung inside the MDS, it will eventually show up in ``ceph health``, -identifying "slow requests are blocked". It may also identify clients as -"failing to respond" or misbehaving in other ways. If the MDS identifies -specific clients as misbehaving, you should investigate why they are doing so. -Generally it will be the result of -1) overloading the system (if you have extra RAM, increase the -"mds cache size" config from its default 100000; having a larger active file set -than your MDS cache is the #1 cause of this!) -2) running an older (misbehaving) client, or -3) underlying RADOS issues. - -Otherwise, you have probably discovered a new bug and should report it to -the developers! - -.. _slow_requests: - -Slow requests (MDS) -------------------- -You can list current operations via the admin socket by running:: - - ceph daemon mds.<name> dump_ops_in_flight - -from the MDS host. Identify the stuck commands and examine why they are stuck. -Usually the last "event" will have been an attempt to gather locks, or sending -the operation off to the MDS log. If it is waiting on the OSDs, fix them. If -operations are stuck on a specific inode, you probably have a client holding -caps which prevent others from using it, either because the client is trying -to flush out dirty data or because you have encountered a bug in CephFS' -distributed file lock code (the file "capabilities" ["caps"] system). - -If it's a result of a bug in the capabilities code, restarting the MDS -is likely to resolve the problem. - -If there are no slow requests reported on the MDS, and it is not reporting -that clients are misbehaving, either the client has a problem or its -requests are not reaching the MDS. - -ceph-fuse debugging -=================== - -ceph-fuse also supports dump_ops_in_flight. See if it has any and where they are -stuck. - -Debug output ------------- - -To get more debugging information from ceph-fuse, try running in the foreground -with logging to the console (``-d``) and enabling client debug -(``--debug-client=20``), enabling prints for each message sent -(``--debug-ms=1``). - -If you suspect a potential monitor issue, enable monitor debugging as well -(``--debug-monc=20``). - - -Kernel mount debugging -====================== - -Slow requests -------------- - -Unfortunately the kernel client does not support the admin socket, but it has -similar (if limited) interfaces if your kernel has debugfs enabled. There -will be a folder in ``sys/kernel/debug/ceph/``, and that folder (whose name will -look something like ``28f7427e-5558-4ffd-ae1a-51ec3042759a.client25386880``) -will contain a variety of files that output interesting output when you ``cat`` -them. These files are described below; the most interesting when debugging -slow requests are probably the ``mdsc`` and ``osdc`` files. - -* bdi: BDI info about the Ceph system (blocks dirtied, written, etc) -* caps: counts of file "caps" structures in-memory and used -* client_options: dumps the options provided to the CephFS mount -* dentry_lru: Dumps the CephFS dentries currently in-memory -* mdsc: Dumps current requests to the MDS -* mdsmap: Dumps the current MDSMap epoch and MDSes -* mds_sessions: Dumps the current sessions to MDSes -* monc: Dumps the current maps from the monitor, and any "subscriptions" held -* monmap: Dumps the current monitor map epoch and monitors -* osdc: Dumps the current ops in-flight to OSDs (ie, file data IO) -* osdmap: Dumps the current OSDMap epoch, pools, and OSDs - -If there are no stuck requests but you have file IO which is not progressing, -you might have a... - -Disconnected+Remounted FS -========================= -Because CephFS has a "consistent cache", if your network connection is -disrupted for a long enough time, the client will be forcibly -disconnected from the system. At this point, the kernel client is in -a bind: it cannot safely write back dirty data, and many applications -do not handle IO errors correctly on close(). -At the moment, the kernel client will remount the FS, but outstanding filesystem -IO may or may not be satisfied. In these cases, you may need to reboot your -client system. - -You can identify you are in this situation if dmesg/kern.log report something like:: - - Jul 20 08:14:38 teuthology kernel: [3677601.123718] ceph: mds0 closed our session - Jul 20 08:14:38 teuthology kernel: [3677601.128019] ceph: mds0 reconnect start - Jul 20 08:14:39 teuthology kernel: [3677602.093378] ceph: mds0 reconnect denied - Jul 20 08:14:39 teuthology kernel: [3677602.098525] ceph: dropping dirty+flushing Fw state for ffff8802dc150518 1099935956631 - Jul 20 08:14:39 teuthology kernel: [3677602.107145] ceph: dropping dirty+flushing Fw state for ffff8801008e8518 1099935946707 - Jul 20 08:14:39 teuthology kernel: [3677602.196747] libceph: mds0 172.21.5.114:6812 socket closed (con state OPEN) - Jul 20 08:14:40 teuthology kernel: [3677603.126214] libceph: mds0 172.21.5.114:6812 connection reset - Jul 20 08:14:40 teuthology kernel: [3677603.132176] libceph: reset on mds0 - -This is an area of ongoing work to improve the behavior. Kernels will soon -be reliably issuing error codes to in-progress IO, although your application(s) -may not deal with them well. In the longer-term, we hope to allow reconnect -and reclaim of data in cases where it won't violate POSIX semantics (generally, -data which hasn't been accessed or modified by other clients). - -Mounting -======== - -Mount 5 Error -------------- - -A mount 5 error typically occurs if a MDS server is laggy or if it crashed. -Ensure at least one MDS is up and running, and the cluster is ``active + -healthy``. - -Mount 12 Error --------------- - -A mount 12 error with ``cannot allocate memory`` usually occurs if you have a -version mismatch between the :term:`Ceph Client` version and the :term:`Ceph -Storage Cluster` version. Check the versions using:: - - ceph -v - -If the Ceph Client is behind the Ceph cluster, try to upgrade it:: - - sudo apt-get update && sudo apt-get install ceph-common - -You may need to uninstall, autoclean and autoremove ``ceph-common`` -and then reinstall it so that you have the latest version. - |