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239 lines
6.9 KiB
ReStructuredText
239 lines
6.9 KiB
ReStructuredText
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cephfs-journal-tool
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===================
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Purpose
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-------
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If a CephFS journal has become damaged, expert intervention may be required
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to restore the filesystem to a working state.
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The ``cephfs-journal-tool`` utility provides functionality to aid experts in
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examining, modifying, and extracting data from journals.
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.. warning::
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This tool is **dangerous** because it directly modifies internal
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data structures of the filesystem. Make backups, be careful, and
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seek expert advice. If you are unsure, do not run this tool.
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Syntax
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------
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::
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cephfs-journal-tool journal <inspect|import|export|reset>
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cephfs-journal-tool header <get|set>
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cephfs-journal-tool event <get|splice|apply> [filter] <list|json|summary|binary>
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The tool operates in three modes: ``journal``, ``header`` and ``event``,
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meaning the whole journal, the header, and the events within the journal
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respectively.
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Journal mode
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------------
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This should be your starting point to assess the state of a journal.
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* ``inspect`` reports on the health of the journal. This will identify any
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missing objects or corruption in the stored journal. Note that this does
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not identify inconsistencies in the events themselves, just that events are
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present and can be decoded.
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* ``import`` and ``export`` read and write binary dumps of the journal
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in a sparse file format. Pass the filename as the last argument. The
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export operation may not work reliably for journals which are damaged (missing
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objects).
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* ``reset`` truncates a journal, discarding any information within it.
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Example: journal inspect
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~~~~~~~~~~~~~~~~~~~~~~~~
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::
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# cephfs-journal-tool journal inspect
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Overall journal integrity: DAMAGED
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Objects missing:
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0x1
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Corrupt regions:
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0x400000-ffffffffffffffff
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Example: Journal import/export
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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::
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# cephfs-journal-tool journal export myjournal.bin
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journal is 4194304~80643
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read 80643 bytes at offset 4194304
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wrote 80643 bytes at offset 4194304 to myjournal.bin
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NOTE: this is a _sparse_ file; you can
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$ tar cSzf myjournal.bin.tgz myjournal.bin
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to efficiently compress it while preserving sparseness.
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# cephfs-journal-tool journal import myjournal.bin
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undump myjournal.bin
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start 4194304 len 80643
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writing header 200.00000000
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writing 4194304~80643
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done.
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.. note::
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It is wise to use the ``journal export <backup file>`` command to make a journal backup
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before any further manipulation.
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Header mode
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-----------
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* ``get`` outputs the current content of the journal header
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* ``set`` modifies an attribute of the header. Allowed attributes are
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``trimmed_pos``, ``expire_pos`` and ``write_pos``.
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Example: header get/set
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~~~~~~~~~~~~~~~~~~~~~~~
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::
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# cephfs-journal-tool header get
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{ "magic": "ceph fs volume v011",
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"write_pos": 4274947,
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"expire_pos": 4194304,
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"trimmed_pos": 4194303,
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"layout": { "stripe_unit": 4194304,
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"stripe_count": 4194304,
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"object_size": 4194304,
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"cas_hash": 4194304,
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"object_stripe_unit": 4194304,
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"pg_pool": 4194304}}
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# cephfs-journal-tool header set trimmed_pos 4194303
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Updating trimmed_pos 0x400000 -> 0x3fffff
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Successfully updated header.
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Event mode
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----------
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Event mode allows detailed examination and manipulation of the contents of the journal. Event
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mode can operate on all events in the journal, or filters may be applied.
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The arguments following ``cephfs-journal-tool event`` consist of an action, optional filter
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parameters, and an output mode:
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::
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cephfs-journal-tool event <action> [filter] <output>
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Actions:
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* ``get`` read the events from the log
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* ``splice`` erase events or regions in the journal
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* ``apply`` extract filesystem metadata from events and attempt to apply it to the metadata store.
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Filtering:
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* ``--range <int begin>..[int end]`` only include events within the range begin (inclusive) to end (exclusive)
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* ``--path <path substring>`` only include events referring to metadata containing the specified string
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* ``--inode <int>`` only include events referring to metadata containing the specified inode
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* ``--type <type string>`` only include events of this type
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* ``--frag <ino>[.frag id]`` only include events referring to this directory fragment
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* ``--dname <string>`` only include events referring to this named dentry within a directory
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fragment (may only be used in conjunction with ``--frag``
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* ``--client <int>`` only include events from this client session ID
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Filters may be combined on an AND basis (i.e. only the intersection of events from each filter).
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Output modes:
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* ``binary``: write each event as a binary file, within a folder whose name is controlled by ``--path``
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* ``json``: write all events to a single file, as a JSON serialized list of objects
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* ``summary``: write a human readable summary of the events read to standard out
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* ``list``: write a human readable terse listing of the type of each event, and
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which file paths the event affects.
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Example: event mode
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~~~~~~~~~~~~~~~~~~~
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::
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# cephfs-journal-tool event get json --path output.json
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Wrote output to JSON file 'output.json'
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# cephfs-journal-tool event get summary
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Events by type:
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NOOP: 2
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OPEN: 2
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SESSION: 2
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SUBTREEMAP: 1
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UPDATE: 43
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# cephfs-journal-tool event get list
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0x400000 SUBTREEMAP: ()
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0x400308 SESSION: ()
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0x4003de UPDATE: (setattr)
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/
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0x40068b UPDATE: (mkdir)
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diralpha
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0x400d1b UPDATE: (mkdir)
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diralpha/filealpha1
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0x401666 UPDATE: (unlink_local)
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stray0/10000000001
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diralpha/filealpha1
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0x40228d UPDATE: (unlink_local)
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diralpha
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stray0/10000000000
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0x402bf9 UPDATE: (scatter_writebehind)
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stray0
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0x403150 UPDATE: (mkdir)
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dirbravo
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0x4037e0 UPDATE: (openc)
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dirbravo/.filebravo1.swp
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0x404032 UPDATE: (openc)
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dirbravo/.filebravo1.swpx
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# cephfs-journal-tool event get --path filebravo1 list
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0x40785a UPDATE: (openc)
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dirbravo/filebravo1
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0x4103ee UPDATE: (cap update)
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dirbravo/filebravo1
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# cephfs-journal-tool event splice --range 0x40f754..0x410bf1 summary
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Events by type:
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OPEN: 1
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UPDATE: 2
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# cephfs-journal-tool event apply --range 0x410bf1.. summary
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Events by type:
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NOOP: 1
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SESSION: 1
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UPDATE: 9
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# cephfs-journal-tool event get --inode=1099511627776 list
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0x40068b UPDATE: (mkdir)
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diralpha
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0x400d1b UPDATE: (mkdir)
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diralpha/filealpha1
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0x401666 UPDATE: (unlink_local)
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stray0/10000000001
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diralpha/filealpha1
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0x40228d UPDATE: (unlink_local)
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diralpha
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stray0/10000000000
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# cephfs-journal-tool event get --frag=1099511627776 --dname=filealpha1 list
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0x400d1b UPDATE: (mkdir)
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diralpha/filealpha1
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0x401666 UPDATE: (unlink_local)
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stray0/10000000001
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diralpha/filealpha1
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# cephfs-journal-tool event get binary --path bin_events
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Wrote output to binary files in directory 'bin_events'
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