btrfs-scrub(8) ============== SYNOPSIS -------- **btrfs scrub** DESCRIPTION ----------- .. include:: ch-scrub-intro.rst SUBCOMMAND ---------- cancel | 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. .. _man-scrub-limit: limit [options] Show or set scrub limits on devices of the given filesystem. ``Options`` -d|--devid DEVID select the device by DEVID to apply the limit -l|--limit SIZE set the limit of the device to SIZE (size units with suffix), or 0 to reset to *unlimited* -a|--all apply the limit to all devices --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 resume [-BdqrR] | 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] | 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 set IO priority class (see :manref:`ionice(1)` manual page) if the IO scheduler configured for the device supports ionice. This is only supported by BFQ or Kyber but is *not* supported by mq-deadline. Please read the section about :docref:`IO limiting `. -n set IO priority classdata (see :manref:`ionice(1)` manpage) -q (deprecated) alias for global *-q* option status [options] | 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 It's possible to set a per-device limit via file :file:`sysfs/fs/btrfs/FSID/devinfo/scrub_speed_max`. In that case the limit is printed on the *Rate:* line if option *-d* is specified, or without it on a single-device filesystem. Read more about tat in section about :docref:`scrub IO limiting `. .. code-block:: none Rate: 989.0MiB/s (limit 1.0G/s) On a multi-device filesystem with at least one device limit the overall stats cannot print the limit without *-d* so there's a not that some limits are set: .. code-block:: none Rate: 36.37MiB/s (some device limits set) 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 `_. SEE ALSO -------- :doc:`mkfs.btrfs`