btrbk/doc/btrbk.conf.5

.TH "btrbk.conf" "5" "2015-11-02" "btrbk v0.21.0" ""
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.SH NAME
btrbk.conf \- btrbk configuration file
.SH SYNOPSIS
.B /etc/btrbk.conf
.br
.B /etc/btrbk/btrbk.conf
.SH DESCRIPTION
The btrbk configuration file specifies which btrfs subvolumes on the
filesystem are to be processed, what target subvolumes should be used
to create the backups, and where the snapshots should be
generated. The retention policy, as well as most other options can be
defined either globally or within a section.
.PP
The options specified always apply to the last section encountered,
superseding the values set in upper-level sections. This means that
global options must be set before any sections are defined.
.SH SECTIONS
.PP
\fBvolume\fR  <volume-directory>|<url>
.RS 4
Directory of a btrfs volume containing the source subvolume(s) to be
backed up. \fI<volume-directory>\fR must be an absolute path and point
to a btrfs volume (or subvolume). Usually the mount point of a btrfs
filesystem mounted with the \fIsubvolid=0\fR option.
.RE
.PP
\fBsubvolume\fR  <subvolume-name>
.RS 4
Subvolume to be backed up, relative to the \fI<volume-directory>\fR
specified in the \fIvolume\fR section. Multiple \fIsubvolume\fR
sections are allowed within \fIvolume\fR sections.
.RE
.PP
\fBtarget\fR  <type> <target-directory>|<url>
.RS 4
Target type and directory where the backup subvolumes are to be
created. See the TARGET TYPES section for supported
\fI<type>\fR. Multiple \fItarget\fR sections are allowed within
\fIsubvolume\fR sections.
.RE
.PP
For the \fIvolume\fR and \fItarget\fR sections, you can specify a
ssh-url instead of a local directory. The syntax for \fI<url>\fR is:
.PP
.RS 4
.nf
ssh://host.xz/path/to/volume
.fi
.RE
.PP
Note that btrfs is very picky on file names (mainly for security
reasons), only the characters [0-9] [a-z] [A-Z] and "._+-@" are
allowed.
.RE
.SH OPTIONS
.PP
\fBtransaction_log\fR  <file>
.RS 4
If set, all transactions (snapshot create, subvolume send-receive,
subvolume delete) as well as abort messages are logged to <file>, in a
space-separated table format.
.RE
.PP
\fBtimestamp_format\fR  short|long
.RS 4
Timestamp format used as postfix for new snapshot subvolume names.
Defaults to \[lq]short\[rq].
.PP
.IP \fBshort\fR
YYYYMMDD[_N]  (e.g. "20150825", "20150825_1")
.IP \fBlong\fR
YYYYMMDD<T>hhmm[_N]  (e.g. "20150825T1531")
.PP
Note that a postfix "_N" is only appended to the timestamp if a
snapshot/backup already exists with the timestamp of current
date/time.
.RE
.PP
\fBsnapshot_dir\fR  <directory>
.RS 4
Directory in which the btrfs snapshots are created, relative to
\fI<volume-directory>\fR of the \fIvolume\fR section. Note that btrbk
does not autmatically create this directory, and the snapshot creation
will fail if it is not present.
.RE
.PP
\fBsnapshot_name\fR <basename>
.RS 4
Base name of the created snapshot (and backup). This option is only
valid in the \fIsubvolume\fR section. Defaults to
\fI<subvolume-name>\fR.
.RE
.PP
\fBsnapshot_create\fR  always|ondemand|onchange|no
.RS 4
If set to \[lq]ondemand\[rq], snapshots are only created if the target
subvolume is reachable (useful if you are tight on disk space and you
only need btrbk for backups to an external disk which is not always
connected).  If set to \[lq]onchange\[rq], snapshots are only created
if the source subvolume has changed since the last snapshot (more
precisely: if the btrfs generation has been increased since the last
snapshot). If set to \[lq]always\[rq], snapshots are always
created. If set to \[lq]no\[rq], the snapshots are never created
(useful in conjunction with the \fIresume_missing\fR option if another
instance of btrbk is taking care of snapshot creation). Defaults to
\[lq]always\[rq].
.RE
.PP
\fBincremental\fR  yes|no|strict
.RS 4
If set, incremental backups are created. If set to \[lq]strict\[rq],
non-incremental (initial) backups are never created. Defaults to
\[lq]yes\[rq].
.RE
.PP
\fBresume_missing\fR  yes|no
.RS 4
If set, the backups in the target directory are compared to the source
snapshots, and missing backups are created if needed (complying to the
target preserve matrix). Defaults to \[lq]yes\[rq].
.RE
.PP
\fBtarget_preserve_daily\fR  all|<number>
.RS 4
How many days of backups should be preserved. Defaults to \[lq]all\[rq].
.RE
.PP
\fBtarget_preserve_weekly\fR  all|<number>
.RS 4
Defines for how many weeks back weekly backups should be
preserved. Every backup created at \fIpreserve_day_of_week\fR (or
the next backup in this week if none was made on the exact day) is
considered as a weekly backup. Defaults to \[lq]0\[rq].
.RE
.PP
\fBtarget_preserve_monthly\fR  all|<number>
.RS 4
Defines for how many months back monthly backups should be
preserved. Every last weekly backup in a month is considered a
monthly backup. Defaults to \[lq]all\[rq].
.RE
.PP
\fBsnapshot_preserve_daily\fR
.PD 0
.PP
\fBsnapshot_preserve_weekly\fR
.PP
\fBsnapshot_preserve_monthly\fR
.RS 4
Defines retention policy for the snapshots, with same semantics as the
\fItarget_preserve_*\fR options.
.RE
.PD
.PP
\fBpreserve_day_of_week\fR  monday|tuesday|...|sunday
.RS 4
Defines on what day a backup/snapshot is considered as a weekly
backup. Defaults to \[lq]sunday\[rq].
.RE
.PP
\fBgroup\fR  <group-name>[,<group-name>]...
.RS 4
Add the current section (volume, subvolume or target) to a
user-defined group, which can be used as filter for several btrbk
commands.
.RE
.PP
\fBssh_identity\fR  <file>
.RS 4
Absolute path to a ssh identity file (private key). Note that if the
private key is password protected, btrbk will prompt for user input,
which is usually not desired.
.RE
.PP
\fBssh_user\fR  <username>
.RS 4
Remote username for ssh. Defaults to \[lq]root\[rq]. Note that you will
have to make sure that the remote user is able to run /sbin/btrfs
(which needs root privileges).
.RE
.PP
\fBssh_port\fR  <port>
.RS 4
Port to connect to on the remote host. Defaults to \[lq]default\[rq]
(the port specified in \fIssh_config\fR, which defaults to 22).
.RE
.PP
\fBssh_compression\fR  yes|no
.RS 4
Enables or disables the compression of ssh connections. Defaults to
\[lq]no\[rq].
.RE
.PP
\fBssh_cipher_spec\fR  <cipher_spec>
.RS 4
Selects the cipher specification for encrypting the session
(comma-separated list of ciphers in order of preference). See the "-c
cipher_spec" option in ssh(1) for more information. Defaults to
\[lq]default\[rq] (the ciphers specified in \fIssh_config\fR).
.RE
.PP
\fBbtrfs_commit_delete\fR  after|each|no
.RS 4
If set, make sure the deletion of snapshot and backup subvolumes are
committed to disk when btrbk terminates. Defaults to \[lq]no\[rq].
.RE
.PP
\fBbtrfs_progs_compat\fR  yes|no \fI*experimental*\fR
.RS 4
Enable compatibility mode for btrfs-progs < 3.17 (\fIbtrfs
--version\fR). This option can be set either globally or within a
\fItarget\fR section.  If enabled, the latest common snapshots are
determined by subvolume names instead of \fIreceived_uuid\fR, which
can lead to false guesses if the snapshot or target subvolumes are
manipulated by hand (moved, deleted).
.RE
.PP
Lines that contain a hash character (#) in the first column are
treated as comments.
.SH TARGET TYPES
.PP
\fBsend-receive\fR
.RS 4
Backup to a btrfs filesystem, using "btrfs send/receive". This is the
recommended (standard) target type. The \fI<target-directory>\fR must
be an absolute path and point to a btrfs volume (or subvolume). See
btrfs-send(8), btrfs-receive(8).
.RE
.PP
\fBraw\fR  \fI*experimental*\fR
.RS 4
Backup to a raw (filesystem independent) file from the output of
btrfs-send(8), with optional compression and encryption.
.PP
Note that the target preserve mechanism is currently disabled for raw
backups (btrbk does not delete any raw files)!
.PP
Additional options for raw targets:
.PP
.RS 4
raw_target_compress  gzip|bzip2|xz|no
.PD 0
.PP
raw_target_encrypt  gpg|no
.PP
gpg_keyring  <file>
.PP
gpg_recipient  <name>
.RE
.PD
.PP
Target file name syntax:
.PP
.RS 4
<snapshot-name>--<received_uuid>[@<parent_uuid>].btrfs[.gz|.bz2|.xz][.gpg]
.RE
.PP
The <parent_uuid> is only set on \fIincremental\fR backups, and points
to the <received_uuid> of the previous backup in a incremental backup
chain.
.PP
For \fIincremental\fR backups ("incremental yes"), please note that:
.IP 1. 4
As soon as a single \fIincremental\fR backup file is lost or
corrupted, all later incremental backups become invalid, as there is
no common parent for the subsequent incremental images anymore. This
might be a good compromise for a vacation backup plan, but for the
long term make sure that a non-incremental backup is triggered from
time to time.
.IP 2. 4
There is currently no support for rotation of incremental backups: if
\fIincremental\fR is set, a full backup must be triggered manually
from time to time in order to be able to delete old backups.
.RE
.SH AVAILABILITY
Please refer to the btrbk project page
\fBhttp://www.digint.ch/btrbk/\fR for further
details.
.SH SEE ALSO
.BR btrbk (1)
.SH AUTHOR
Axel Burri <axel@tty0.ch>