Title: btrfs-scrub Author: [FIXME: author] [see http://docbook.sf.net/el/author] Generator: DocBook XSL Stylesheets v1.79.0 <http://docbook.sf.net/> Date: 07/28/2017 Manual: Btrfs Manual Source: Btrfs v4.12 Language: English
NAMEbtrfs-scrub - scrub btrfs filesystem, verify block checksums
btrfs scrub <subcommand> <args>
btrfs scrub is used to scrub a btrfs filesystem, which will read all data and metadata blocks from all devices and verify checksums. Automatically repair corrupted blocks if therecqs a correct copy available.
Scrub is not a filesystem checker (fsck) and does not verify nor repair structural damage in the filesystem.
The user is supposed to run it manually or via a periodic system service. The recommended period is a month but could be less. The estimated device bandwidth utilization is about 80% on an idle filesystem. The IO priority class is by default idle so background scrub should not interfere with normal filesystem operation significantly.
The scrubbing status is recorded in /var/lib/btrfs/ in textual files named scrub.status.UUID for a filesystem identified by the given UUID. (Progress state is communicated through a named pipe in file scrub.progress.UUID in the same directory.) The status file is updated every 5 seconds. A resumed scrub will continue from the last saved position.
If a scrub is running on the filesystem identified by
If a device is specified, the corresponding filesystem is found and btrfs scrub cancel behaves as if it was called on that filesystem.
resume [-BdqrR] [-c <ioprio_class> -n <ioprio_classdata>] <path>|<device>
Resume a cancelled or interrupted scrub on the filesystem identified by
or on a given
Does not start a new scrub if the last scrub finished successfully.
see scrub start.
start [-BdqrRf] [-c <ioprio_class> -n <ioprio_classdata>] <path>|<device>
Start a scrub on all devices of the filesystem identified by
or on a single
device. If a scrub is already running, the new one fails.
Without options, scrub is started as a background process.
The default IO priority of scrub is the idle class. The priority can be configured similar to the ionice(1) syntax using -c and -n options.
- do not background and print scrub statistics when finished
- print separate statistics for each device of the filesystem (-B only) at the end
- be quiet, omit error messages and statistics
- run in read-only mode, do not attempt to correct anything, can be run on a read-only filesystem
- print raw statistics per-device instead of a summary
- set IO priority class (see ionice(1) manpage)
- set IO priority classdata (see ionice(1) manpage)
- 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
status [-d] <path>|<device>
Show status of a running scrub for the filesystem identified by
or for the specified
If no scrub is running, show statistics of the last finished or cancelled scrub for that filesystem or device.
- print separate statistics for each device of the filesystem
btrfs scrub returns a zero exit status if it succeeds. Non zero is returned in case of failure:
- scrub couldncqt be performed
- there is nothing to resume
- scrub found uncorrectable errors
btrfs is part of btrfs-progs. Please refer to the btrfs wiki m[blue]btrfs.wiki.kernel.orgm for further details.