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| -rw-r--r-- | doc/cephfs/disaster-recovery-experts.rst | 41 |
1 files changed, 22 insertions, 19 deletions
diff --git a/doc/cephfs/disaster-recovery-experts.rst b/doc/cephfs/disaster-recovery-experts.rst index 7677b42f47e..b01a3dfde6a 100644 --- a/doc/cephfs/disaster-recovery-experts.rst +++ b/doc/cephfs/disaster-recovery-experts.rst @@ -21,43 +21,46 @@ Advanced: Metadata repair tools Journal export -------------- -Before attempting dangerous operations, make a copy of the journal like so: +Before attempting any dangerous operation, make a copy of the journal by +running the following command: -:: +.. prompt:: bash # - cephfs-journal-tool journal export backup.bin + cephfs-journal-tool journal export backup.bin -Note that this command may not always work if the journal is badly corrupted, -in which case a RADOS-level copy should be made (http://tracker.ceph.com/issues/9902). +If the journal is badly corrupted, this command might not work. If the journal +is badly corrupted, make a RADOS-level copy +(http://tracker.ceph.com/issues/9902). Dentry recovery from journal ---------------------------- If a journal is damaged or for any reason an MDS is incapable of replaying it, -attempt to recover what file metadata we can like so: +attempt to recover file metadata by running the following command: -:: +.. prompt:: bash # - cephfs-journal-tool event recover_dentries summary + cephfs-journal-tool event recover_dentries summary -This command by default acts on MDS rank 0, pass --rank=<n> to operate on other ranks. +By default, this command acts on MDS rank ``0``. Pass the option ``--rank=<n>`` +to the ``cephfs-journal-tool`` command to operate on other ranks. -This command will write any inodes/dentries recoverable from the journal -into the backing store, if these inodes/dentries are higher-versioned -than the previous contents of the backing store. If any regions of the journal -are missing/damaged, they will be skipped. +This command writes all inodes and dentries recoverable from the journal into +the backing store, but only if these inodes and dentries are higher-versioned +than the existing contents of the backing store. Any regions of the journal +that are missing or damaged will be skipped. -Note that in addition to writing out dentries and inodes, this command will update -the InoTables of each 'in' MDS rank, to indicate that any written inodes' numbers -are now in use. In simple cases, this will result in an entirely valid backing +In addition to writing out dentries and inodes, this command updates the +InoTables of each ``in`` MDS rank, to indicate that any written inodes' numbers +are now in use. In simple cases, this will result in an entirely valid backing store state. .. warning:: - The resulting state of the backing store is not guaranteed to be self-consistent, - and an online MDS scrub will be required afterwards. The journal contents - will not be modified by this command, you should truncate the journal + The resulting state of the backing store is not guaranteed to be + self-consistent, and an online MDS scrub will be required afterwards. The + journal contents will not be modified by this command. Truncate the journal separately after recovering what you can. Journal truncation |