btrfs-progs/Documentation/btrfs-scrub.rst
David Sterba a0137082de btrfs-progs: docs: formatting updates
- use :file: and :command:
- simplify manual page references
- add more web links
- typo fixes
- more cross-references

Signed-off-by: David Sterba <dsterba@suse.com>
2023-07-26 14:59:10 +02:00

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btrfs-scrub(8)
==============
SYNOPSIS
--------
**btrfs scrub** <subcommand> <args>
DESCRIPTION
-----------
.. include:: ch-scrub-intro.rst
SUBCOMMAND
----------
cancel <path>|<device>
If a scrub is running on the filesystem identified by *path* or
*device*, cancel it.
If a *device* is specified, the corresponding filesystem is found and
:command:`btrfs scrub cancel` behaves as if it was called on that filesystem.
The progress is saved in the status file so :command:`btrfs scrub resume` can
continue from the last position.
resume [-BdqrR] <path>|<device>
Resume a cancelled or interrupted scrub on the filesystem identified by
*path* or on a given *device*. The starting point is read from the
status file if it exists.
This does not start a new scrub if the last scrub finished successfully.
``Options``
see :command:`scrub start`.
.. _man-scrub-start:
start [-BdrRf] <path>|<device>
Start a scrub on all devices of the mounted filesystem identified by
*path* or on a single *device*. If a scrub is already running, the new
one will not start. A device of an unmounted filesystem cannot be
scrubbed this way.
Without options, scrub is started as a background process. The
automatic repairs of damaged copies are performed by default for block
group profiles with redundancy. No-repair can be enabled by option *-r*.
``Options``
-B
do not background and print scrub statistics when finished
-d
print separate statistics for each device of the filesystem
(*-B* only) at the end
-r
run in read-only mode, do not attempt to correct anything, can
be run on a read-only filesystem
-R
raw print mode, print full data instead of summary
-f
force starting new scrub even if a scrub is already running,
this can useful when scrub status file is damaged and reports a
running scrub although it is not, but should not normally be
necessary
``Deprecated options``
-c <ioprio_class>
set IO priority class (see ``ionice(1)`` manpage) if the IO
scheduler configured for the device supports ionice. This is
not supported byg BFQ or Kyber but is *not* supported by
mq-deadline.
-n <ioprio_classdata>
set IO priority classdata (see ``ionice(1)`` manpage)
-q
(deprecated) alias for global *-q* option
status [options] <path>|<device>
Show status of a running scrub for the filesystem identified by *path*
or for the specified *device*.
If no scrub is running, show statistics of the last finished or
cancelled scrub for that filesystem or device.
``Options``
-d
print separate statistics for each device of the filesystem
-R
print all raw statistics without postprocessing as returned by
the status ioctl
--raw
print all numbers raw values in bytes without the *B* suffix
--human-readable
print human friendly numbers, base 1024, this is the default
--iec
select the 1024 base for the following options, according to
the IEC standard
--si
select the 1000 base for the following options, according to the SI standard
--kbytes
show sizes in KiB, or kB with --si
--mbytes
show sizes in MiB, or MB with --si
--gbytes
show sizes in GiB, or GB with --si
--tbytes
show sizes in TiB, or TB with --si
A status on a filesystem without any error looks like the following:
.. code-block:: none
# btrfs scrub start /
# btrfs scrub status /
UUID: 76fac721-2294-4f89-a1af-620cde7a1980
Scrub started: Wed Apr 10 12:34:56 2023
Status: running
Duration: 0:00:05
Time left: 0:00:05
ETA: Wed Apr 10 12:35:01 2023
Total to scrub: 28.32GiB
Bytes scrubbed: 13.76GiB (48.59%)
Rate: 2.75GiB/s
Error summary: no errors found
With some errors found:
.. code-block:: none
Error summary: csum=72
Corrected: 2
Uncorrectable: 72
Unverified: 0
* *Corrected* -- number of bad blocks that were repaired from another copy
* *Uncorrectable* -- errors detected at read time but not possible to repair from other copy
* *Unverified* -- transient errors, first read failed but a retry
succeeded, may be affected by lower layers that group or split IO requests
* *Error summary* -- followed by a more detailed list of errors found
* *csum* -- checksum mismatch
* *super* -- super block errors, unless the error is fixed
immediately, the next commit will overwrite superblock
* *verify* -- metadata block header errors
* *read* -- blocks can't be read due to IO errors
EXIT STATUS
-----------
**btrfs scrub** returns a zero exit status if it succeeds. Non zero is
returned in case of failure:
1
scrub couldn't be performed
2
there is nothing to resume
3
scrub found uncorrectable errors
AVAILABILITY
------------
**btrfs** is part of btrfs-progs. Please refer to the documentation at
`https://btrfs.readthedocs.io <https://btrfs.readthedocs.io>`_.
SEE ALSO
--------
:doc:`mkfs.btrfs`