NAME¶btrfs-scrub - scrub btrfs filesystem, verify block checksums
SYNOPSIS¶btrfs scrub <subcommand> <args>
DESCRIPTION¶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 there’s 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 filesytem. 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. (An itermediate progress is communicated through a named pipe in file scrub.progress.UUID in the same directory.) The status file is updated periodically every 5 seconds. An resumed scrub will continue from the last saved position.
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>
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>
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.
status [-d] <path>|<device>
If no scrub is running, show statistics of the last finished or cancelled scrub for that filesystem or device.
EXIT STATUS¶btrfs scrub returns a zero exit status if it succeeds. Non zero is returned in case of failure.
AVAILABILITY¶btrfs is part of btrfs-progs. Please refer to the btrfs wiki http://btrfs.wiki.kernel.org for further details.
SEE ALSO¶mkfs.btrfs(8), ionice(1)