Man page - ceph-bluestore-tool(8)

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Manual

CEPH-BLUESTORE-TOOL(8) Ceph CEPH-BLUESTORE-TOOL(8)

ceph-bluestore-tool - bluestore administrative tool

ceph-bluestore-tool command
[ --dev device ... ]
[ -i osd_id ]
[ --path osd path ]
[ --out-dir dir ]
[ --log-file | -l filename ]
[ --deep ]
ceph-bluestore-tool fsck|repair --path osd path [ --deep ]
ceph-bluestore-tool qfsck       --path osd path
ceph-bluestore-tool allocmap    --path osd path
ceph-bluestore-tool restore_cfb --path osd path
ceph-bluestore-tool show-label --dev device ...
ceph-bluestore-tool show-label-at --dev device --offset lba...
ceph-bluestore-tool prime-osd-dir --dev device --path osd path
ceph-bluestore-tool bluefs-export --path osd path --out-dir dir
ceph-bluestore-tool bluefs-bdev-new-wal --path osd path --dev-target new-device
ceph-bluestore-tool bluefs-bdev-new-db --path osd path --dev-target new-device
ceph-bluestore-tool bluefs-bdev-migrate --path osd path --dev-target new-device --devs-source device1 [--devs-source device2]
ceph-bluestore-tool free-dump|free-score --path osd path [ --allocator block/bluefs-wal/bluefs-db/bluefs-slow ]
ceph-bluestore-tool bluefs-stats --path osd path
ceph-bluestore-tool bluefs-files --path osd path
ceph-bluestore-tool reshard --path osd path --sharding new sharding [ --sharding-ctrl control string ]
ceph-bluestore-tool show-sharding --path osd path
ceph-bluestore-tool trim --path osd path
ceph-bluestore-tool zap-device --dev dev path
ceph-bluestore-tool revert-wal-to-plain --path osd path

ceph-bluestore-tool is a utility to perform low-level administrative operations on a BlueStore instance.

help

show help


fsck [ --deep ] (on|off) or (yes|no) or (1|0) or (true|false)

run consistency check on BlueStore metadata. If --deep is specified, also read all object data and verify checksums.


repair

Run a consistency check and repair any errors we can.


qfsck

run consistency check on BlueStore metadata comparing allocator data (from RocksDB CFB when exists and if not uses allocation-file) with ONodes state.


allocmap

performs the same check done by qfsck and then stores a new allocation-file (command is disabled by default and requires a special build)


restore_cfb

Reverses changes done by the new NCB code (either through ceph restart or when running allocmap command) and restores RocksDB B Column-Family (allocator-map).


bluefs-export

Export the contents of BlueFS (i.e., RocksDB files) to an output directory.


bluefs-bdev-sizes --path osd path

Print the device sizes, as understood by BlueFS, to stdout.


bluefs-bdev-expand --path osd path

Instruct BlueFS to check the size of its block devices and, if they have expanded, make use of the additional space. Please note that only the new files created by BlueFS will be allocated on the preferred block device if it has enough free space, and the existing files that have spilled over to the slow device will be gradually removed when RocksDB performs compaction. In other words, if there is any data spilled over to the slow device, it will be moved to the fast device over time.


bluefs-bdev-new-wal --path osd path --dev-target new-device

Adds WAL device to BlueFS, fails if WAL device already exists.


bluefs-bdev-new-db --path osd path --dev-target new-device

Adds DB device to BlueFS, fails if DB device already exists.


bluefs-bdev-migrate --dev-target new-device --devs-source device1 [--devs-source device2]

Moves BlueFS data from source device(s) to the target device. Source devices (except the main one) are removed on success. Expands the target storage (updates the size label), making "bluefs-bdev-expand" unnecessary. The target device can be either a new device or a device that is already attached. If the device is a new device, it is added to the OSD replacing one of the source devices. The following replacement rules apply (in the order of precedence, stop on the first match):
  • if the source list has DB volume - the target device replaces it.
  • if the source list has WAL volume - the target device replaces it.
  • if the source list has slow volume only - the operation isn't permitted and requires explicit allocation via a new-DB/new-WAL command.





show-label --dev device [...]

Show device label(s). The label may be printed while an OSD is running.


show-label-at --dev device --offset

*
lba*[...]
Show device label at specific disk location. Dedicated DB/WAL volumes have a single label at offset 0. Main device could have valid labels at multiple locations: 0/1GiB/10GiB/100GiB/1000GiB. The labels at some locations might not exist though. The label may be printed while an OSD is running.


free-dump --path osd path [ --allocator block/bluefs-wal/bluefs-db/bluefs-slow ]

Dump all free regions in allocator.


free-score --path osd path [ --allocator block/bluefs-wal/bluefs-db/bluefs-slow ]

Give a [0-1] number that represents quality of fragmentation in allocator. 0 represents case when all free space is in one chunk. 1 represents worst possible fragmentation.


bluefs-stats --path osd path

Shows summary of BlueFS occupied space with split on devices: block/db/wal and roles: wal/log/db.


bluefs-files --path osd path

Lists all BlueFS managed files, printing name, size and space used on devices.


reshard --path osd path --sharding new sharding [ --resharding-ctrl control string ]

Changes sharding of BlueStore's RocksDB. Sharding is build on top of RocksDB column families. This option allows to test performance of new sharding without need to redeploy OSD. Resharding is usually a long process, which involves walking through entire RocksDB key space and moving some of them to different column families. Option --resharding-ctrl provides performance control over resharding process. Interrupted resharding will prevent OSD from running. Interrupted resharding does not corrupt data. It is always possible to continue previous resharding, or select any other sharding scheme, including reverting to original one.


show-sharding --path osd path

Show sharding that is currently applied to BlueStore's RocksDB.


trim --path osd path

An SSD that has been used heavily may experience performance degradation. This operation uses TRIM / discard to free unused blocks from BlueStore and BlueFS block devices, and allows the drive to perform more efficient internal housekeeping. If BlueStore runs with discard enabled, this option may not be useful.

zap-device --dev dev path

Zeros all device label locations. This effectively makes device appear empty.

revert-wal-to-plain --path osd path

Changes WAL files from envelope mode to the legacy plain mode. Useful for downgrades, or if you might want to disable this new feature (bluefs_wal_envelope_mode).


Add device to the list of devices to consider

Operate as OSD osd_id. Connect to monitor for OSD specific options. If monitor is unavailable, add --no-mon-config to read from ceph.conf instead.

Add device to the list of devices to consider as sources for migrate operation

Specify target device migrate operation or device to add for adding new DB/WAL.

Specify an osd path. In most cases, the device list is inferred from the symlinks present in osd path. This is usually simpler than explicitly specifying the device(s) with --dev. Not necessary if -i osd_id is provided.

Output directory for bluefs-export

file to log to

debug log level. Default is 30 (extremely verbose), 20 is very verbose, 10 is verbose, and 1 is not very verbose.

deep scrub/repair (read and validate object data, not just metadata)

Useful for free-dump and free-score actions. Selects allocator(s).

Provides control over resharding process. Specifies how often refresh RocksDB iterator, and how large should commit batch be before committing to RocksDB. Option format is: <iterator_refresh_bytes>/<iterator_refresh_keys>/<batch_commit_bytes>/<batch_commit_keys> Default: 10000000/10000/1000000/1000

Any configuration option that is accepted by OSD can be also passed to ceph-bluestore-tool. Useful to provide necessary configuration options when access to monitor/ceph.conf is impossible and -i option cannot be used.

Every BlueStore block device has a block label at the beginning of the device. Main device might optionaly have additional labels at different locations for the sake of OSD robustness. You can dump the contents of the label with:

ceph-bluestore-tool show-label --dev *device*


The main device will have a lot of metadata, including information that used to be stored in small files in the OSD data directory. The auxiliary devices (db and wal) will only have the minimum required fields (OSD UUID, size, device type, birth time). The main device contains additional label copies at offsets: 1GiB, 10GiB, 100GiB and 1000GiB. Corrupted labels are fixed as part of repair:

ceph-bluestore-tool repair --dev *device*


You can generate the content for an OSD data directory that can start up a BlueStore OSD with the prime-osd-dir command:

ceph-bluestore-tool prime-osd-dir --dev *main device* --path /var/lib/ceph/osd/ceph-*id*


Some versions of BlueStore were susceptible to BlueFS log growing extremely large - beyond the point of making booting OSD impossible. This state is indicated by booting that takes very long and fails in _replay function.

ceph-bluestore-tool fsck --path osd path --bluefs_replay_recovery=true
ceph-bluestore-tool fsck --path osd path --bluefs_replay_recovery=true --bluefs_replay_recovery_disable_compact=true

If above fsck is successful fix procedure can be applied.

ceph-bluestore-tool is part of Ceph, a massively scalable, open-source, distributed storage system. Please refer to the Ceph documentation at https://docs.ceph.com for more information.

ceph-osd(8)

2010-2014, Inktank Storage, Inc. and contributors. Licensed under Creative Commons Attribution Share Alike 3.0 (CC-BY-SA-3.0)

December 17, 2025 dev