SYNOPSIS
--------
-*btrfstune* [options] <dev> [<dev>...]
+*btrfstune* [options] <device> [<device>...]
DESCRIPTION
-----------
-*btrfstune* can be used to enable, disable or set various filesystem
+*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.
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 filesystem. Please refer to
-the respective section in `btrfs`(5).
+Some of the features could be also enabled on a mounted filesystem by other
+means. Please refer to the 'FILESYSTEM FEATURES' in `btrfs`(5).
OPTIONS
-------
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)
+
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'.
+
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.
+
+This deprecated tool exists for historical reasons but is still in use today.
+Its functionality will be merged to the main tool, at which time *btrfstune*
+will be declared obsolete and scheduled for removal.
SEE ALSO
--------