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BTRFSTUNE(8) | Btrfs Manual | BTRFSTUNE(8) |
NAME¶
btrfstune - tune various filesystem parametersSYNOPSIS¶
btrfstune [options] <dev> [<dev>...]DESCRIPTION¶
btrfstune can be used to enable, disable or set various filesystem parameters. The filesystem must be unmounted. The common usecase is to enable features that were not enabled at mkfs time. Please make sure that you have kernel support for the features. You can find a complete list of features and kernel version of their introduction at https://btrfs.wiki.kernel.org/index.php/Changelog#By_feature . Also, the manual page mkfs.btrfs(8) contains more details about the features. Some of the features could be enabled on a mounted filesytem. Please refer to the respective section in btrfs(5).OPTIONS¶
-S <0|1>Enable seeding on a given device. Value 1 will enable
seeding, 0 will disable it.
A seeding filesystem is forced to be mounted read-only. A new device can be
added to the filesystem and will capture all writes keeping the seeding device
intact.
-r
(since kernel: 3.7)
Enable extended inode refs (hardlink limit per file in a directory is 65536),
enabled by mkfs feature extref. -x:: (since kernel: 3.10)
Enable skinny metadata extent refs (more efficient representation of extents),
enabled by mkfs feature skinny-metadata.
All newly created extents will use the new representation. To completely switch
the entire filesystem, run a full balance of the metadata. Please refer to
btrfs-balance(8). -n:: (since kernel: 3.14)
Enable no-holes feature (more efficient representation of file holes), enabled
by mkfs feature no-holes. -f:: Allow dangerous changes, e.g. clear the
seeding flag or change fsid. Make sure that you are aware of the dangers. -u::
Change fsid to a randomly generated UUID or continue previous fsid change
operation in case it was interrupted. -U <UUID>:: Change fsid to
UUID.
The UUID should be a 36 bytes string in printf(3) format
"%08x-%04x-%04x-%04x-%012x". If there is a previous
unfinished fsid change, it will continue only if the UUID matches the
unfinished one or if you use the option -u.
EXIT STATUS¶
btrfstune returns 0 if no error happened, 1 otherwise.COMPATIBILITY NOTE¶
This tool exists for historical reasons but is still in use today. The functionality is about to be merged to the main tool someday and btrfstune will become deprecated and removed afterwards.SEE ALSO¶
btrfs(5), btrfs-balance(8), mkfs.btrfs(8)10/02/2016 | Btrfs v4.7.3 |