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NAME | SYNOPSIS | DESCRIPTION | SUBCOMMAND | EXIT STATUS | AVAILABILITY | SEE ALSO | COLOPHON |
BTRFS-RESCUE(8) Btrfs Manual BTRFS-RESCUE(8)
btrfs-rescue - Recover a damaged btrfs filesystem
btrfs rescue <subcommand> <args>
btrfs rescue is used to try to recover a damaged btrfs filesystem.
chunk-recover [options] <device>
Recover the chunk tree by scanning the devices
Options
-y
assume an answer of yes to all questions.
-v
verbose mode.
-h
help.
Note
Since chunk-recover will scan the whole device, it will be VERY
slow especially executed on a large device.
super-recover [options] <device>
Recover bad superblocks from good copies.
Options
-y
assume an answer of yes to all questions.
-v
verbose mode.
zero-log <device>
clear the filesystem log tree
This command will clear the filesystem log tree. This may fix a
specific set of problem when the filesystem mount fails due to
the log replay. See below for sample stacktraces that may show up
in system log.
The common case where this happens has been fixed a long time
ago, so it is unlikely that you will see this particular problem,
but the utility is kept around.
Note
clearing the log may lead to loss of changes that were made
since the last transaction commit. This may be up to 30
seconds (default commit period) or less if the commit was
implied by other filesystem activity.
One can determine whether zero-log is needed according to the
kernel backtrace:
? replay_one_dir_item+0xb5/0xb5 [btrfs]
? walk_log_tree+0x9c/0x19d [btrfs]
? btrfs_read_fs_root_no_radix+0x169/0x1a1 [btrfs]
? btrfs_recover_log_trees+0x195/0x29c [btrfs]
? replay_one_dir_item+0xb5/0xb5 [btrfs]
? btree_read_extent_buffer_pages+0x76/0xbc [btrfs]
? open_ctree+0xff6/0x132c [btrfs]
+ If the errors are like above, then zero-log should be used to clear
the log and the filesystem may be mounted normally again. The
keywords to look for are open_ctree which says that it’s during mount
and function names that contain replay, recover or log_tree.
btrfs rescue returns a zero exit status if it succeeds. Non zero is
returned in case of failure.
btrfs is part of btrfs-progs. Please refer to the btrfs wiki
http://btrfs.wiki.kernel.org for further details.
mkfs.btrfs(8), btrfs-scrub(8), btrfs-check(8)
This page is part of the btrfs-progs (btrfs filesystem tools)
project. Information about the project can be found at
⟨https://btrfs.wiki.kernel.org/index.php/Btrfs_source_repositories⟩.
If you have a bug report for this manual page, see
⟨https://btrfs.wiki.kernel.org/index.php/Problem_FAQ#How_do_I_report_bugs_and_issues.3F⟩.
This page was obtained from the project's upstream Git repository
⟨git://git.kernel.org/pub/scm/linux/kernel/git/kdave/btrfs-progs.git⟩
on 2017-07-05. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-to-
date source for the page, or you have corrections or improvements to
the information in this COLOPHON (which is not part of the original
manual page), send a mail to man-pages@man7.org
Btrfs v4.6.1 07/05/2017 BTRFS-RESCUE(8)
Pages that refer to this page: btrfs(8), btrfs-check(8), btrfs-restore(8)