345 lines
9.5 KiB
ReStructuredText
345 lines
9.5 KiB
ReStructuredText
Btrfs has a sysfs interface to provide extra knobs.
|
|
|
|
The top level path is :file:`/sys/fs/btrfs/`, and the main directory layout is the following:
|
|
|
|
============================= =================================== ========
|
|
Relative Path Description Version
|
|
============================= =================================== ========
|
|
features/ All supported features 3.14+
|
|
<UUID>/ Mounted fs UUID 3.14+
|
|
<UUID>/allocation/ Space allocation info 3.14+
|
|
<UUID>/features/ Features of the filesystem 3.14+
|
|
<UUID>/devices/<DEVID>/ Symlink to each block device sysfs 5.6+
|
|
<UUID>/devinfo/<DEVID>/ Btrfs specific info for each device 5.6+
|
|
<UUID>/qgroups/ Global qgroup info 5.9+
|
|
<UUID>/qgroups/<LEVEL>_<ID>/ Info for each qgroup 5.9+
|
|
<UUID>/discard/ Discard stats and tunables 6.1+
|
|
============================= =================================== ========
|
|
|
|
For :file:`/sys/fs/btrfs/features/` directory, each file means a supported feature
|
|
for the current kernel.
|
|
|
|
For :file:`/sys/fs/btrfs/<UUID>/features/` directory, each file means an enabled
|
|
feature for the mounted filesystem.
|
|
|
|
The features shares the same name in section
|
|
:ref:`FILESYSTEM FEATURES<man-btrfs5-filesystem-features>`.
|
|
|
|
Files in :file:`/sys/fs/btrfs/<UUID>/` directory are:
|
|
|
|
bg_reclaim_threshold
|
|
(RW, since: 5.19)
|
|
|
|
Used space percentage of total device space to start auto block group claim.
|
|
Mostly for zoned devices.
|
|
|
|
checksum
|
|
(RO, since: 5.5)
|
|
|
|
The checksum used for the mounted filesystem.
|
|
This includes both the checksum type (see section
|
|
:ref:`CHECKSUM ALGORITHMS<man-mkfs-checksum-algorithms>`)
|
|
and the implemented driver (mostly shows if it's hardware accelerated).
|
|
|
|
clone_alignment
|
|
(RO, since: 3.16)
|
|
|
|
The bytes alignment for *clone* and *dedupe* ioctls.
|
|
|
|
commit_stats
|
|
(RW, since: 6.0)
|
|
|
|
The performance statistics for btrfs transaction commit since the first
|
|
mount. Mostly for debugging purposes.
|
|
|
|
Writing into this file will reset the maximum commit duration
|
|
(*max_commit_ms*) to 0. The file looks like:
|
|
|
|
.. code-block:: none
|
|
|
|
commits 70649
|
|
last_commit_ms 2
|
|
max_commit_ms 131
|
|
total_commit_ms 170840
|
|
|
|
* *commits* - number of transaction commits since the first mount
|
|
* *last_commit_ms* - duration in milliseconds of the last commit
|
|
* *max_commit_ms* - maximum time a transaction commit took since first mount or last reset
|
|
* *total_commit_ms* - sum of all transaction commit times
|
|
|
|
exclusive_operation
|
|
(RO, since: 5.10)
|
|
|
|
Shows the running exclusive operation.
|
|
Check section
|
|
:ref:`FILESYSTEM EXCLUSIVE OPERATIONS<man-btrfs5-fileysstem-exclusive-operations>`
|
|
for details.
|
|
|
|
generation
|
|
(RO, since: 5.11)
|
|
|
|
Show the generation of the mounted filesystem.
|
|
|
|
label
|
|
(RW, since: 3.14)
|
|
|
|
Show the current label of the mounted filesystem.
|
|
|
|
metadata_uuid
|
|
(RO, since: 5.0)
|
|
|
|
Shows the metadata uuid of the mounted filesystem.
|
|
Check `metadata_uuid` feature for more details.
|
|
|
|
nodesize
|
|
(RO, since: 3.14)
|
|
|
|
Show the nodesize of the mounted filesystem.
|
|
|
|
quota_override
|
|
(RW, since: 4.13)
|
|
|
|
Shows the current quota override status.
|
|
0 means no quota override.
|
|
1 means quota override, quota can ignore the existing limit settings.
|
|
|
|
read_policy
|
|
(RW, since: 5.11)
|
|
|
|
Shows the current balance policy for reads.
|
|
Currently only "pid" (balance using pid value) is supported.
|
|
|
|
sectorsize
|
|
(RO, since: 3.14)
|
|
|
|
Shows the sectorsize of the mounted filesystem.
|
|
|
|
|
|
temp_fsid
|
|
(RO, since 6.7)
|
|
|
|
Indicate that this filesystem got assigned a temporary FSID at mount time,
|
|
making possible to mount devices with the same FSID.
|
|
|
|
Files and directories in :file:`/sys/fs/btrfs/<UUID>/allocations` directory are:
|
|
|
|
global_rsv_reserved
|
|
(RO, since: 3.14)
|
|
|
|
The used bytes of the global reservation.
|
|
|
|
global_rsv_size
|
|
(RO, since: 3.14)
|
|
|
|
The total size of the global reservation.
|
|
|
|
`data/`, `metadata/` and `system/` directories
|
|
(RO, since: 5.14)
|
|
|
|
Space info accounting for the 3 chunk types.
|
|
Mostly for debug purposes.
|
|
|
|
Files in :file:`/sys/fs/btrfs/<UUID>/allocations/{data,metadata,system}` directory are:
|
|
|
|
bg_reclaim_threshold
|
|
(RW, since: 5.19)
|
|
|
|
Reclaimable space percentage of block group's size (excluding
|
|
permanently unusable space) to reclaim the block group.
|
|
Can be used on regular or zoned devices.
|
|
|
|
bytes_*
|
|
(RO)
|
|
|
|
Values of the corresponding data structures for the given block group
|
|
type and profile.
|
|
|
|
chunk_size
|
|
(RW, since: 6.0)
|
|
|
|
Shows the chunk size. Can be changed for data and metadata.
|
|
Cannot be set for zoned devices.
|
|
|
|
size_classes
|
|
(RO, since: 6.3)
|
|
|
|
Numbers of block groups of a given classes based on heuristics that
|
|
measure extent length, age and fragmentation.
|
|
|
|
.. code-block:: none
|
|
|
|
none 136
|
|
small 374
|
|
medium 282
|
|
large 93
|
|
|
|
Files in :file:`/sys/fs/btrfs/<UUID>/devinfo/<DEVID>` directory are:
|
|
|
|
error_stats:
|
|
(RO, since: 5.14)
|
|
|
|
Shows device stats of this device, same as :command:`btrfs device stats` (:doc:`btrfs-device`).
|
|
|
|
.. code-block:: none
|
|
|
|
write_errs 0
|
|
read_errs 0
|
|
flush_errs 0
|
|
corruption_errs 0
|
|
generation_errs 0
|
|
|
|
fsid:
|
|
(RO, since: 5.17)
|
|
|
|
Shows the fsid which the device belongs to.
|
|
It can be different than the `<UUID>` if it's a seed device.
|
|
|
|
in_fs_metadata
|
|
(RO, since: 5.6)
|
|
|
|
Shows whether we have found the device.
|
|
Should always be 1, as if this turns to 0, the `<DEVID>` directory
|
|
would get removed automatically.
|
|
|
|
missing
|
|
(RO, since: 5.6)
|
|
|
|
Shows whether the device is missing.
|
|
|
|
replace_target
|
|
(RO, since: 5.6)
|
|
|
|
Shows whether the device is the replace target.
|
|
If no dev-replace is running, this value should be 0.
|
|
|
|
scrub_speed_max
|
|
(RW, since: 5.14)
|
|
|
|
Shows the scrub speed limit for this device. The unit is Bytes/s.
|
|
0 means no limit. The value can be set but is not persisent.
|
|
|
|
writeable
|
|
(RO, since: 5.6)
|
|
|
|
Show if the device is writeable.
|
|
|
|
Files in :file:`/sys/fs/btrfs/<UUID>/qgroups/` directory are:
|
|
|
|
enabled
|
|
(RO, since: 6.1)
|
|
|
|
Shows if qgroup is enabled.
|
|
Also, if qgroup is disabled, the `qgroups` directory would
|
|
be removed automatically.
|
|
|
|
inconsistent
|
|
(RO, since: 6.1)
|
|
|
|
Shows if the qgroup numbers are inconsistent.
|
|
If 1, it's recommended to do a qgroup rescan.
|
|
|
|
drop_subtree_threshold
|
|
(RW, since: 6.1)
|
|
|
|
Shows the subtree drop threshold to automatically mark qgroup inconsistent.
|
|
|
|
When dropping large subvolumes with qgroup enabled, there would be a huge
|
|
load for qgroup accounting.
|
|
If we have a subtree whose level is larger than or equal to this value,
|
|
we will not trigger qgroup account at all, but mark qgroup inconsistent to
|
|
avoid the huge workload.
|
|
|
|
Default value is 8, where no subtree drop can trigger qgroup.
|
|
|
|
Lower value can reduce qgroup workload, at the cost of extra qgroup rescan
|
|
to re-calculate the numbers.
|
|
|
|
Files in :file:`/sys/fs/btrfs/<UUID>/<LEVEL>_<ID>/` directory are:
|
|
|
|
exclusive
|
|
(RO, since: 5.9)
|
|
|
|
Shows the exclusively owned bytes of the qgroup.
|
|
|
|
limit_flags
|
|
(RO, since: 5.9)
|
|
|
|
Shows the numeric value of the limit flags.
|
|
If 0, means no limit implied.
|
|
|
|
max_exclusive
|
|
(RO, since: 5.9)
|
|
|
|
Shows the limits on exclusively owned bytes.
|
|
|
|
max_referenced
|
|
(RO, since: 5.9)
|
|
|
|
Shows the limits on referenced bytes.
|
|
|
|
referenced
|
|
(RO, since: 5.9)
|
|
|
|
Shows the referenced bytes of the qgroup.
|
|
|
|
rsv_data
|
|
(RO, since: 5.9)
|
|
|
|
Shows the reserved bytes for data.
|
|
|
|
rsv_meta_pertrans
|
|
(RO, since: 5.9)
|
|
|
|
Shows the reserved bytes for per transaction metadata.
|
|
|
|
rsv_meta_prealloc
|
|
(RO, since: 5.9)
|
|
|
|
Shows the reserved bytes for preallocated metadata.
|
|
|
|
Files in :file:`/sys/fs/btrfs/<UUID>/discard/` directory are:
|
|
|
|
discardable_bytes
|
|
(RO, since: 6.1)
|
|
|
|
Shows amount of bytes that can be discarded in the async discard and
|
|
nodiscard mode.
|
|
|
|
discardable_extents
|
|
(RO, since: 6.1)
|
|
|
|
Shows number of extents to be discarded in the async discard and
|
|
nodiscard mode.
|
|
|
|
discard_bitmap_bytes
|
|
(RO, since: 6.1)
|
|
|
|
Shows amount of discarded bytes from data tracked as bitmaps.
|
|
|
|
discard_extent_bytes
|
|
(RO, since: 6.1)
|
|
|
|
Shows amount of discarded extents from data tracked as bitmaps.
|
|
|
|
discard_bytes_saved
|
|
(RO, since: 6.1)
|
|
|
|
Shows the amount of bytes that were reallocated without being discarded.
|
|
|
|
kbps_limit
|
|
(RW, since: 6.1)
|
|
|
|
Tunable limit of kilobytes per second issued as discard IO in the async
|
|
discard mode.
|
|
|
|
iops_limit
|
|
(RW, since: 6.1)
|
|
|
|
Tunable limit of number of discard IO operations to be issued in the
|
|
async discard mode.
|
|
|
|
max_discard_size
|
|
(RW, since: 6.1)
|
|
|
|
Tunable limit for size of one IO discard request.
|