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--- software:linux:btrfs [2015/06/22 00:23] – superwizard
+++ software:linux:btrfs [2016/11/17 03:26] (current) – superwizard
@@ Line 1: / Line 1: @@
+====== Scripts for btrfs maintenance tasks like periodic scrub ======
+From: https://github.com/kdave/btrfsmaintenance
+<code>
+Great Documentation
+Scripts for btrfs maintenance tasks like periodic scrub, balance, trim or defrag on selected
+mountpoints or directories.
+</code>
+====== btrfs check ======
+From: https://btrfs.wiki.kernel.org/index.php/Manpage/btrfs-check
+<code>
+btrfs check /dev/sb2
+btrfs check --repair \dev\sb2
+</code>
+====== btrfs scrub ======
+From: http://marc.merlins.org/perso/btrfs/post_2014-03-19_Btrfs-Tips_-Btrfs-Scrub-and-Btrfs-Filesystem-Repair.html
+From: https://btrfs.wiki.kernel.org/index.php/Manpage/btrfs-scrub
+<code>
+btrfs scrub start -Bd $mountpoint
+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.
+start [-BdqrRf] [-c <ioprio_class> -n <ioprio_classdata>] <path>|<device>
+Start a scrub on all devices of the filesystem identified by path 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.
+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
+-q
+be quiet, omit error messages and statistics
+-r
+run in read-only mode, do not attempt to correct anything, can be run on a read-only filesystem
+-R
+print raw statistics per-device instead of a summary
+-c <ioprio_class>
+set IO priority class (see ionice(1) manpage)
+-n <ioprio_classdata>
+set IO priority classdata (see ionice(1) manpage)
+-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
+status [-d] <path>|<device>
+</code>
+====== resize partition ======
+From: http://unix.stackexchange.com/questions/239765/how-to-fix-btrfs-superblock-error-after-resize-shrink-btrfs-couldnt-get-super
+<code>
+Fix
+First, a live system was booted to reduce the risk of damage while the system is running on a
+filesystem that's bigger than the partition it's on.
+Mount the filesystem:
+mount /dev/sda2 /mnt/tmp
+First shrink the second device to 50 GB - 1 GB = 49 GB to avoid rounding errors:
+btrfs filesystem resize 2:49g /mnt/tmp
+Resize it to fill the 50 GB partition:
+btrfs filesystem resize 2:max /mnt/tmp
+Check btrfs filesystem show, both devices should have the right size:
+devid    1 size 50.00GiB used 43.03GiB path /dev/sda2
+devid    2 size 50.00GiB used 43.03GiB path /dev/sdb2
+Unmount, reboot, the error should be gone.
+</code>
+====== BTRFS restoring a corrupt filesystem from another “tree location” ======
+From: http://ram.kossboss.com/btrfs-restoring-a-corrupt-filesystem-from-another-tree-location/
+<code>
+Here is how you restore a really corrupt btrfs filesystem using btrfs restore.
+PRE STEPS (realizing the filesystem is really corrupt by trying simple mounts and
+restores):
+* assume your volume name is /dev/md127 and that you have an available /root folder
+to dump temp data to and that you will be dumping your restore to /USB
+* you can change any of those variable if thats not the case
+Here we assume the filesystem is so corrupt that its not mounting regulary:
+# mount /dev/md127 /data
+mount: wrong fs type, bad option, bad superblock on /dev/md127,
+       missing codepage or helper program, or other error
+       In some cases useful info is found in syslog - try
+       dmesg | tail  or so
+</code>
 ====== btrfs file system ======