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doc/cephfs: edit troubleshooting.rst
Edit the section "In-memory log dumps" in doc/cephfs/troubleshooting.rst. Signed-off-by: Zac Dover <[email protected]> (cherry picked from commit bc1aa66) fixup Co-authored-by: Anthony D'Atri <[email protected]> Signed-off-by: Zac Dover <[email protected]>
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doc/cephfs/troubleshooting.rst

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@@ -438,36 +438,53 @@ To disable debug logging, run a command of the following form:
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In-memory Log Dump
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==================
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In-memory logs can be dumped by setting ``mds_extraordinary_events_dump_interval``
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during a lower level debugging (log level < 10). ``mds_extraordinary_events_dump_interval``
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is the interval in seconds for dumping the recent in-memory logs when there is an Extra-Ordinary event.
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In-memory logs can be dumped by setting
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``mds_extraordinary_events_dump_interval`` when
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the log level is set to less than ``10``.
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``mds_extraordinary_events_dump_interval`` is the interval in seconds for
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dumping the recent in-memory logs when there is an extraordinary event.
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The Extra-Ordinary events are classified as:
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Extraordinary events include the following:
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* Client Eviction
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* Missed Beacon ACK from the monitors
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* Missed Internal Heartbeats
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In-memory Log Dump is disabled by default to prevent log file bloat in a production environment.
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The below commands consecutively enables it::
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In-memory log dump is disabled by default. This prevents production
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environments from experiencing log file bloat by default.
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$ ceph config set mds debug_mds <log_level>/<gather_level>
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$ ceph config set mds mds_extraordinary_events_dump_interval <seconds>
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Run the following two commands in order to enable in-memory log dumping:
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The ``log_level`` should be < 10 and ``gather_level`` should be >= 10 to enable in-memory log dump.
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When it is enabled, the MDS checks for the extra-ordinary events every
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``mds_extraordinary_events_dump_interval`` seconds and if any of them occurs, MDS dumps the
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in-memory logs containing the relevant event details in ceph-mds log.
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#.
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.. prompt:: bash $
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.. note:: For higher log levels (log_level >= 10) there is no reason to dump the In-memory Logs and a
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lower gather level (gather_level < 10) is insufficient to gather In-memory Logs. Thus a
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log level >=10 or a gather level < 10 in debug_mds would prevent enabling the In-memory Log Dump.
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In such cases, when there is a failure it's required to reset the value of
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mds_extraordinary_events_dump_interval to 0 before enabling using the above commands.
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ceph config set mds debug_mds <log_level>/<gather_level>
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Set ``log_level`` to a value of less than ``10``. Set ``gather_level`` to a
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value greater than ``10``. When those two values have been set, in-memory
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log dump is enabled.
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#.
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.. prompt:: bash #
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ceph config set mds mds_extraordinary_events_dump_interval <seconds>
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When in-memory log dumping is enabled, the MDS checks for
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extraordinary events every ``mds_extraordinary_events_dump_interval``
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seconds. If any extraordinary event occurs, the MDS dumps the in-memory logs
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that contain relevant event details to the Ceph MDS log.
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.. note:: When higher log levels are set (``log_level`` greater than or equal
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to ``10``) there is no reason to dump the in-memory logs. A lower gather
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level (``gather_level`` less than ``10``) is insufficient to gather in-
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memory logs. This means that a log level of greater than or equal to ``10``
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or a gather level of less than ``10`` in ``debug_mds`` prevents enabling
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in-memory-log dumping. In such cases, if there is a failure, you must reset
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the value of ``mds_extraordinary_events_dump_interval`` to ``0`` before
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enabling the use of the above commands.
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The In-memory Log Dump can be disabled using::
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Disable in-memory log dumping by running the following command:
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.. prompt:: bash #
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$ ceph config set mds mds_extraordinary_events_dump_interval 0
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ceph config set mds mds_extraordinary_events_dump_interval 0
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Filesystems Become Inaccessible After an Upgrade
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================================================

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