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author | Nicholas D Steeves <nsteeves@gmail.com> | 2016-04-23 00:41:30 +0100 |
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committer | Nicholas D Steeves <nsteeves@gmail.com> | 2016-04-23 00:41:30 +0100 |
commit | cec572daccafa1e912cbed363df6f84687778c6f (patch) | |
tree | 7d99ab9f73d25c1ed8eaf6393f6374edf5316b03 /Documentation/btrfstune.asciidoc |
btrfs-progs (4.4.1-1.1) unstable; urgency=medium
* Non-maintainer upload.
* New upstream release.
* Rename package to btrfs-progs (Closes: #780081)
* Update standards version to 3.9.7 (no changes needed).
* debian/control: Add "Breaks" per Gianfranco Costamagna's suggestion
* Change lintian override to reflect package rename
* Switch from using postinst and postrm to using triggers
per Christian Seiler's recommendation.
# imported from the archive
Diffstat (limited to 'Documentation/btrfstune.asciidoc')
-rw-r--r-- | Documentation/btrfstune.asciidoc | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/Documentation/btrfstune.asciidoc b/Documentation/btrfstune.asciidoc new file mode 100644 index 00000000..f5cf15e7 --- /dev/null +++ b/Documentation/btrfstune.asciidoc @@ -0,0 +1,75 @@ +btrfstune(8) +============ + +NAME +---- +btrfstune - tune various filesystem parameters + +SYNOPSIS +-------- +*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 . + +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:: +Enable extended inode refs (hardlink limit per file in a directory is 65536), +enabled by mkfs feature 'extref'. Since kernel 3.7. +-x:: +Enable skinny metadata extent refs (more efficient representation of extents), +enabled by mkfs feature 'skinny-metadata'. Since kernel 3.10. +-n:: +Enable no-holes feature (more efficient representation of file holes), enabled +by mkfs feature 'no-holes'. Since kernel 3.14. +-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'. + +WARNING: Cancelling or interrupting a UUID change operation will make the +filesystem temporarily unmountable. To fix it, rerun 'btrfstune -u' to restore +the UUID and let it complete. + +WARNING: Clearing the seeding flag on a device may be dangerous. +If a previously-seeding device is changed, all filesystems that used that +device will become unmountable. Setting the seeding flag back will not fix +that. + +A valid usecase is 'seeding device as a base image'. Clear the seeding +flag, update the filesystem and make it seeding again, provided that it's ok +to throw away all filesystems built on top of the previous base. + +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 +-------- +`mkfs.btrfs`(8) |