224 lines
7.7 KiB
ReStructuredText
224 lines
7.7 KiB
ReStructuredText
btrfs-scrub(8)
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==============
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SYNOPSIS
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--------
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**btrfs scrub** <subcommand> <args>
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DESCRIPTION
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-----------
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.. include:: ch-scrub-intro.rst
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SUBCOMMAND
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----------
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cancel <path>|<device>
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If a scrub is running on the filesystem identified by *path* or
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*device*, cancel it.
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If a *device* is specified, the corresponding filesystem is found and
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:command:`btrfs scrub cancel` behaves as if it was called on that filesystem.
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The progress is saved in the status file so :command:`btrfs scrub resume` can
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continue from the last position.
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.. _man-scrub-limit:
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limit [options] <path>
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Show or set scrub limits on devices of the given filesystem.
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``Options``
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-d|--devid DEVID
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select the device by DEVID to apply the limit
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-l|--limit SIZE
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set the limit of the device to SIZE (size units with suffix),
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or 0 to reset to *unlimited*
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-a|--all
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apply the limit to all devices
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--raw
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print all numbers raw values in bytes without the *B* suffix
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--human-readable
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print human friendly numbers, base 1024, this is the default
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--iec
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select the 1024 base for the following options, according to
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the IEC standard
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--si
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select the 1000 base for the following options, according to the SI standard
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--kbytes
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show sizes in KiB, or kB with --si
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--mbytes
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show sizes in MiB, or MB with --si
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--gbytes
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show sizes in GiB, or GB with --si
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--tbytes
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show sizes in TiB, or TB with --si
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resume [-BdqrR] <path>|<device>
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Resume a cancelled or interrupted scrub on the filesystem identified by
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*path* or on a given *device*. The starting point is read from the
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status file if it exists.
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This does not start a new scrub if the last scrub finished successfully.
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``Options``
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see :command:`scrub start`.
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.. _man-scrub-start:
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start [-BdrRf] <path>|<device>
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Start a scrub on all devices of the mounted filesystem identified by
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*path* or on a single *device*. If a scrub is already running, the new
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one will not start. A device of an unmounted filesystem cannot be
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scrubbed this way.
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Without options, scrub is started as a background process. The
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automatic repairs of damaged copies are performed by default for block
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group profiles with redundancy. No-repair can be enabled by option *-r*.
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``Options``
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-B
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do not background and print scrub statistics when finished
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-d
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print separate statistics for each device of the filesystem
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(*-B* only) at the end
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-r
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run in read-only mode, do not attempt to correct anything, can
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be run on a read-only filesystem
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-R
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raw print mode, print full data instead of summary
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-f
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force starting new scrub even if a scrub is already running,
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this can useful when scrub status file is damaged and reports a
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running scrub although it is not, but should not normally be
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necessary
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``Deprecated options``
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-c <ioprio_class>
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set IO priority class (see :manref:`ionice(1)` manual page) if the IO
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scheduler configured for the device supports ionice. This is
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only supported by BFQ or Kyber but is *not* supported by
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mq-deadline. Please read the section about
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:docref:`IO limiting <btrfs-scrub:scrub-io-limiting>`.
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-n <ioprio_classdata>
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set IO priority classdata (see :manref:`ionice(1)` manpage)
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-q
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(deprecated) alias for global *-q* option
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status [options] <path>|<device>
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Show status of a running scrub for the filesystem identified by *path*
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or for the specified *device*.
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If no scrub is running, show statistics of the last finished or
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cancelled scrub for that filesystem or device.
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``Options``
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-d
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print separate statistics for each device of the filesystem
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-R
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print all raw statistics without postprocessing as returned by
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the status ioctl
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--raw
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print all numbers raw values in bytes without the *B* suffix
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--human-readable
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print human friendly numbers, base 1024, this is the default
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--iec
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select the 1024 base for the following options, according to
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the IEC standard
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--si
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select the 1000 base for the following options, according to the SI standard
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--kbytes
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show sizes in KiB, or kB with --si
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--mbytes
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show sizes in MiB, or MB with --si
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--gbytes
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show sizes in GiB, or GB with --si
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--tbytes
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show sizes in TiB, or TB with --si
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A status on a filesystem without any error looks like the following:
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.. code-block:: none
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# btrfs scrub start /
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# btrfs scrub status /
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UUID: 76fac721-2294-4f89-a1af-620cde7a1980
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Scrub started: Wed Apr 10 12:34:56 2023
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Status: running
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Duration: 0:00:05
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Time left: 0:00:05
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ETA: Wed Apr 10 12:35:01 2023
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Total to scrub: 28.32GiB
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Bytes scrubbed: 13.76GiB (48.59%)
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Rate: 2.75GiB/s
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Error summary: no errors found
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With some errors found:
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.. code-block:: none
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Error summary: csum=72
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Corrected: 2
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Uncorrectable: 72
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Unverified: 0
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* *Corrected* -- number of bad blocks that were repaired from another copy
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* *Uncorrectable* -- errors detected at read time but not possible to repair from other copy
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* *Unverified* -- transient errors, first read failed but a retry
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succeeded, may be affected by lower layers that group or split IO requests
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* *Error summary* -- followed by a more detailed list of errors found
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* *csum* -- checksum mismatch
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* *super* -- super block errors, unless the error is fixed
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immediately, the next commit will overwrite superblock
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* *verify* -- metadata block header errors
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* *read* -- blocks can't be read due to IO errors
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It's possible to set a per-device limit via file
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:file:`sysfs/fs/btrfs/FSID/devinfo/scrub_speed_max`. In that case
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the limit is printed on the *Rate:* line if option *-d* is specified,
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or without it on a single-device filesystem. Read more about tat in
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section about :docref:`scrub IO limiting <btrfs-scrub:scrub-io-limiting>`.
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.. code-block:: none
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Rate: 989.0MiB/s (limit 1.0G/s)
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On a multi-device filesystem with at least one device limit the
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overall stats cannot print the limit without *-d* so there's a not that
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some limits are set:
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.. code-block:: none
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Rate: 36.37MiB/s (some device limits set)
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EXIT STATUS
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-----------
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**btrfs scrub** returns a zero exit status if it succeeds. Non zero is
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returned in case of failure:
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1
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scrub couldn't be performed
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2
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there is nothing to resume
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3
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scrub found uncorrectable errors
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AVAILABILITY
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------------
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**btrfs** is part of btrfs-progs. Please refer to the documentation at
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`https://btrfs.readthedocs.io <https://btrfs.readthedocs.io>`_.
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SEE ALSO
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--------
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:doc:`mkfs.btrfs`
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