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diff --git a/Documentation/btrfstune.8 b/Documentation/btrfstune.8 new file mode 100644 index 00000000..b83d9e9d --- /dev/null +++ b/Documentation/btrfstune.8 @@ -0,0 +1,142 @@ +'\" t +.\" Title: btrfstune +.\" Author: [FIXME: author] [see http://www.docbook.org/tdg5/en/html/author] +.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/> +.\" Date: 12/05/2018 +.\" Manual: Btrfs Manual +.\" Source: Btrfs v4.19.1 +.\" Language: English +.\" +.TH "BTRFSTUNE" "8" "12/05/2018" "Btrfs v4\&.19\&.1" "Btrfs Manual" +.\" ----------------------------------------------------------------- +.\" * Define some portability stuff +.\" ----------------------------------------------------------------- +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.\" http://bugs.debian.org/507673 +.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.ie \n(.g .ds Aq \(aq +.el .ds Aq ' +.\" ----------------------------------------------------------------- +.\" * set default formatting +.\" ----------------------------------------------------------------- +.\" disable hyphenation +.nh +.\" disable justification (adjust text to left margin only) +.ad l +.\" ----------------------------------------------------------------- +.\" * MAIN CONTENT STARTS HERE * +.\" ----------------------------------------------------------------- +.SH "NAME" +btrfstune \- tune various filesystem parameters +.SH "SYNOPSIS" +.sp +\fBbtrfstune\fR [options] \fI<device>\fR [\fI<device>\fR\&...] +.SH "DESCRIPTION" +.sp +\fBbtrfstune\fR can be used to enable, disable, or set various filesystem parameters\&. The filesystem must be unmounted\&. +.sp +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 \m[blue]\fBhttps://btrfs\&.wiki\&.kernel\&.org/index\&.php/Changelog#By_feature\fR\m[] \&. Also, the manual page \fBmkfs\&.btrfs\fR(8) contains more details about the features\&. +.sp +Some of the features could be also enabled on a mounted filesystem by other means\&. Please refer to the \fIFILESYSTEM FEATURES\fR in \fBbtrfs\fR(5)\&. +.SH "OPTIONS" +.PP +\-S \fI<0|1>\fR +.RS 4 +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\&. +.RE +.PP +\-r +.RS 4 +(since kernel: 3\&.7) +.sp +Enable extended inode refs (hardlink limit per file in a directory is 65536), enabled by mkfs feature +\fIextref\fR\&. +.RE +.PP +\-x +.RS 4 +(since kernel: 3\&.10) +.sp +Enable skinny metadata extent refs (more efficient representation of extents), enabled by mkfs feature +\fIskinny\-metadata\fR\&. +.sp +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 +\fBbtrfs\-balance\fR(8)\&. +.RE +.PP +\-n +.RS 4 +(since kernel: 3\&.14) +.sp +Enable no\-holes feature (more efficient representation of file holes), enabled by mkfs feature +\fIno\-holes\fR\&. +.RE +.PP +\-f +.RS 4 +Allow dangerous changes, e\&.g\&. clear the seeding flag or change fsid\&. Make sure that you are aware of the dangers\&. +.RE +.PP +\-u +.RS 4 +Change fsid to a randomly generated UUID or continue previous fsid change operation in case it was interrupted\&. +.RE +.PP +\-U \fI<UUID>\fR +.RS 4 +Change fsid to +\fIUUID\fR\&. +.sp +The +\fIUUID\fR +should be a 36 bytes string in +\fBprintf\fR(3) format +\fI"%08x\-%04x\-%04x\-%04x\-%012x"\fR\&. If there is a previous unfinished fsid change, it will continue only if the +\fIUUID\fR +matches the unfinished one or if you use the option +\fI\-u\fR\&. +.RE +.if n \{\ +.sp +.\} +.RS 4 +.it 1 an-trap +.nr an-no-space-flag 1 +.nr an-break-flag 1 +.br +.ps +1 +\fBWarning\fR +.ps -1 +.br +.sp +Cancelling or interrupting a UUID change operation will make the filesystem temporarily unmountable\&. To fix it, rerun \fIbtrfstune \-u\fR to restore the UUID and let it complete\&. +.sp .5v +.RE +.if n \{\ +.sp +.\} +.RS 4 +.it 1 an-trap +.nr an-no-space-flag 1 +.nr an-break-flag 1 +.br +.ps +1 +\fBWarning\fR +.ps -1 +.br +.sp +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 \fIseeding device as a base image\fR\&. Clear the seeding flag, update the filesystem and make it seeding again, provided that it\(cqs OK to throw away all filesystems built on top of the previous base\&. +.sp .5v +.RE +.SH "EXIT STATUS" +.sp +\fBbtrfstune\fR returns 0 if no error happened, 1 otherwise\&. +.SH "COMPATIBILITY NOTE" +.sp +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 \fBbtrfstune\fR will be declared obsolete and scheduled for removal\&. +.SH "SEE ALSO" +.sp +\fBbtrfs\fR(5), \fBbtrfs\-balance\fR(8), \fBmkfs\&.btrfs\fR(8) |