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Diffstat (limited to 'Documentation/btrfs-select-super.8')
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diff --git a/Documentation/btrfs-select-super.8 b/Documentation/btrfs-select-super.8 new file mode 100644 index 00000000..e56b290a --- /dev/null +++ b/Documentation/btrfs-select-super.8 @@ -0,0 +1,111 @@ +'\" t +.\" Title: btrfs-select-super +.\" 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 "BTRFS\-SELECT\-SUPER" "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" +btrfs-select-super \- overwrite primary superblock with a backup copy +.SH "SYNOPSIS" +.sp +\fBbtrfs\-select\-super\fR \-s number \fI<device>\fR +.SH "DESCRIPTION" +.sp +Destructively overwrite all copies of the superblock with a specified copy\&. This helps in certain cases, for example when write barriers were disabled during a power failure and not all superblocks were written, or if the primary superblock is damaged, eg\&. accidentally overwritten\&. +.sp +The filesystem specified by \fIdevice\fR must not be mounted\&. +.if n \{\ +.sp +.\} +.RS 4 +.it 1 an-trap +.nr an-no-space-flag 1 +.nr an-break-flag 1 +.br +.ps +1 +\fBNote\fR +.ps -1 +.br +.sp +\fBPrior to overwriting the primary superblock, please make sure that the backup copies are valid!\fR +.sp .5v +.RE +.sp +To dump a superblock use the \fBbtrfs inspect\-internal dump\-super\fR command\&. +.sp +Then run the check (in the non\-repair mode) using the command \fBbtrfs check \-s\fR where \fI\-s\fR specifies the superblock copy to use\&. +.sp +Superblock copies exist in the following offsets on the device: +.sp +.RS 4 +.ie n \{\ +\h'-04'\(bu\h'+03'\c +.\} +.el \{\ +.sp -1 +.IP \(bu 2.3 +.\} +primary: +\fI64KiB\fR +(65536) +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04'\(bu\h'+03'\c +.\} +.el \{\ +.sp -1 +.IP \(bu 2.3 +.\} +1st copy: +\fI64MiB\fR +(67108864) +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04'\(bu\h'+03'\c +.\} +.el \{\ +.sp -1 +.IP \(bu 2.3 +.\} +2nd copy: +\fI256GiB\fR +(274877906944) +.RE +.sp +A superblock size is \fI4KiB\fR (4096)\&. +.SH "OPTIONS" +.PP +\-s|\-\-super \fI<superblock>\fR +.RS 4 +use \*(Aqsuperblock\(cqth superblock copy, valid values are 0 1 or 2 if the respective superblock offset is within the device size +.RE +.SH "SEE ALSO" +.sp +\fBbtrfs\-inspect\-internal\fR(8), \fBbtrfsck check\fR(8) |