ambiser
/
btrbk
mirror of https://github.com/digint/btrbk
9
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
btrbk/doc/btrbk.conf.5.asciidoc

705 lines
25 KiB
Plaintext
Raw Blame History

btrbk.conf(5)
=============
:date: 2023-03-25
:release-version: 0.32.6
:man manual: Btrbk Manual
:man source: Btrbk {release-version}
NAME
----
btrbk.conf - btrbk configuration file
SYNOPSIS
--------
[verse]
/etc/btrbk.conf
/etc/btrbk/btrbk.conf
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.
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.
Blank lines are ignored. A hash character (#) starts a comment
extending until end of line.
SECTIONS
--------
*volume* <volume-directory>|<url> (optional)::
Absolute path pointing to a btrfs file system containing the
source subvolume(s) to be backed up. Usually the mount point of a
btrfs filesystem mounted with the 'subvolid=5' option.
*subvolume* <subvolume-name>::
Subvolume to be backed up, relative to the '<volume-directory>' of
the 'volume' section, or absolute if the 'volume' section is
omitted. Accepts wildcard character "*".
+
--
Note that if this subvolume is btrfs root (id=5), it needs to have a
valid UUID, which is not the case for file systems created with
btrfs-progs < 4.16.
--
*target* [send-receive|raw] <target-directory>|<url>::
Target directory where the backup subvolumes are to be
created. The optional target type defaults to ``send-receive'',
see <<_target_types,TARGET TYPES>> below for details.
+
--
Multiple 'target' sections are allowed, in any context: a 'target'
defined in 'volume' or global context will be used for all underlying
'subvolume' sections (hint: run "btrbk list" or "btrbk config print"
to see the resulting configuration).
--
If a '<url>' is specified, btrbk actions (shell commands) are executed
remotely via ssh, using the <<_ssh_options,SSH Options>> described
below. Accepted formats are:
ssh://<hostname>[:<port>]/<directory>
<hostname>:<directory>
Where '<hostname>' is either a host name, an IPv4 address in
dotted-decimal form, or an IP literal encapsulated within square
brackets (e.g. "[2001:db8::7]").
If you are connecting to virtual machines, consider configuring
several 'volume' sections for a '<hostname>', with distinct '<port>'
numbers for each machine.
OPTIONS
-------
The options described here can be specified in 'global context' as
well as 'volume', 'subvolume' and 'target' sections, unless stated
otherwise.
=== Basic Options
*timestamp_format* short|long|long-iso::
Timestamp format used as postfix for new snapshot subvolume
names. Defaults to ``long''.
+
--
ifndef::backend-docbook,backend-manpage[]
[horizontal]
endif::backend-docbook,backend-manpage[]
*short*;; +YYYYMMDD[_N]+ (e.g. "20150825", "20150825_1")
*long*;; +YYYYMMDD<T>hhmm[_N]+ (e.g. "20150825T1531")
*long-iso*;; +YYYYMMDD<T>hhmmss&plusmn;hhmm[_N]+ (e.g. "20150825T153123+0200")
--
+
Note that a postfix "_N" is appended to the timestamp if a snapshot or
backup already exists with the timestamp of current date/time.
+
Use ``long-iso'' if you want to make sure that btrbk never
creates ambiguous time stamps (which can happen if multiple
snapshots are created during a daylight saving time clock
change).
+
Note that using ``long-iso'' has implications on the scheduling, see
<<_reference_time,Reference Time>> below.
*snapshot_dir* <directory>::
Directory in which the btrfs snapshots are created, relative to
'<volume-directory>' of the 'volume' section, or absolute if the
'volume' section is omitted. Note that btrbk does not
automatically create this directory, and the snapshot creation
will fail if it is not present.
*snapshot_name* <basename>::
Base name of the created snapshot (and backup). This option is
only valid in the 'subvolume' section. Defaults to
'<subvolume-name>'.
*snapshot_create* always|onchange|ondemand|no::
If set to ``always'', snapshots are always created. If set to
``onchange'', snapshots are only created if the last snapshot is
not up-to-date, i.e. the source subvolume has changed (more
precisely: the btrfs generation has been increased) since the last
snapshot was created. If set to ``ondemand'', snapshots are only
created if at least one 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 ``no'',
the snapshots are never created (useful if another instance of
btrbk is taking care of snapshot creation). Defaults to
``always''.
*incremental* yes|no|strict::
If set, incremental backups are created. If set to ``strict'',
non-incremental (initial) backups are never created, and
incremental backups are restricted to 'related parents' (by
parent-uuid relationship). Defaults to ``yes''.
+
--
Note that even if the parent-uuid chain is broken, snapshots and
backups can still share data (which is especially true for backups
created with 'incremental' option enabled), and are perfectly suitable
as parents for incremental send-receive operations. But as btrbk can
not be certain about this, such operations are disallowed in
"incremental strict" mode.
--
*noauto* yes|no::
If set, the context is skipped by all btrbk actions unless
explicitly enabled by a matching btrbk '<filter>' command line
argument (e.g. "btrbk run myfilter").
=== Grouping Options
*group* <group-name> [<group-name>]...::
Add the current section (volume, subvolume or target) to
user-defined groups, which can be used as filter for most btrbk
commands (see btrbk(1) FILTER STATEMENTS). This option can be set
multiple times within the same context.
=== Retention Policy Options
*preserve_day_of_week* monday|tuesday|...|sunday::
Defines on what day a snapshot/backup is considered to be a
"weekly" backup. Weekly, monthly and yearly backups are preserved
on this day of week (see <<_retention_policy,RETENTION POLICY>>
below). Defaults to ``sunday''.
*preserve_hour_of_day* [0..23]::
Defines after what time (in full hours since midnight) a
snapshot/backup is considered to be a "daily" backup. Daily,
weekly, monthly and yearly backups are preserved on this hour (see
<<_retention_policy,RETENTION POLICY>> below). Ignored on
snapshots or backups without time information ('timestamp_format
short'). Defaults to ``0''.
*snapshot_preserve* no|<retention_policy>::
Set retention policy for snapshots (see
<<_retention_policy,RETENTION POLICY>> below). If set to ``no'',
preserve snapshots according to 'snapshot_preserve_min'
only. Defaults to ``no''.
+
--
Note that 'snapshot_preserve' has no effect if 'snapshot_preserve_min'
is set to ``all'' (the default).
--
*snapshot_preserve_min* all|latest|<number>{h,d,w,m,y}::
Preserve all snapshots for a minimum amount of hours (h), days
(d), weeks (w), months (m) or years (y), regardless of how many
there are. If set to ``all'', preserve all snapshots forever. If
set to ``latest'', preserve latest snapshot. Defaults to ``all''.
*target_preserve* no|<retention_policy>::
Set retention policy for backups (see
<<_retention_policy,RETENTION POLICY>> below). If set to ``no'',
preserve backups according to 'target_preserve_min' only. Defaults
to ``no''.
+
--
Note that 'target_preserve' has no effect if 'target_preserve_min' is
set to ``all'' (the default).
--
*target_preserve_min* all|latest|no|<number>{h,d,w,m,y}::
Preserve all backups for a minimum amount of hours (h), days (d),
weeks (w), months (m) or years (y), regardless of how many there
are. If set to ``all'', preserve all backups forever. If set to
``latest'', always preserve the latest backup (useful in
conjunction with "target_preserve no", if you want to keep the
latest backup only). If set to ``no'', only the backups following
the 'target_preserve' policy are created. Defaults to ``all''.
*archive_preserve* no|<retention_policy>::
Set retention policy for archives ("btrbk archive" command), with
same semantics as 'target_preserve'.
*archive_preserve_min* all|latest|no|<number>{h,d,w,m,y}::
Set retention policy for archives ("btrbk archive" command), with
same semantics as 'target_preserve_min'.
*archive_exclude* <pattern>::
Exclude subvolumes matching <pattern> from archiving. The pattern
accepts wildcard character "*", and is matched against the end of
the pathname.
=== SSH Options
*ssh_identity* <file>|no::
Absolute path to a ssh identity file (private key). If not set,
the ssh default is used (see ssh(1), "-i identity_file"). Note
that if the identity key is password protected and no
authentication agent is used, btrbk will prompt for user input on
every connection attempt.
*ssh_user* <username>|no::
Remote username for ssh. Defaults to ``root''. Make sure the
remote user is able to run "btrfs" with root privileges (see
option 'backend' for details). If set to ``no'', the ssh default
is used.
*ssh_compression* yes|no::
Enables or disables the compression of ssh connections. Defaults
to ``no''. Note that if *stream_compress* is enabled, ssh
compression will always be disabled for send/receive operations.
*ssh_cipher_spec* default|<cipher_spec>::
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 ``default'' (the ciphers specified in ssh_config(5)).
=== Data Stream Options
*stream_compress* <compress_command>|no::
Compress the btrfs send stream before transferring it from/to
remote locations. Defaults to ``no''. If enabled, make sure that
'<compress_command>' is available on the source and target
hosts. Supported '<compress_command>': gzip, pigz, bzip2, pbzip2,
bzip3, xz, lzo, lz4, zstd.
*stream_compress_level* default|<number>::
Compression level for the specified '<compress_command>'. Refer to
the related man-page for details (usually [1..9], where 1 means
fastest compression). Defaults to ``default'' (the default
compression level of '<compress_command>').
*stream_compress_long* default|<number>::
Enable long distance matching for the specified
'<compress_command>'. Refer to the related man-page for details.
Only supported for "zstd".
*stream_compress_threads* default|<number>::
Number of threads to use for <compress_command>. Only supported
for "pigz", "pbzip2", "bzip3", "zstd" and recent versions of "xz".
*stream_compress_adapt* default|<number>::
Enable adaptive compression for <compress_command>. Only supported
for "zstd" (version >= 1.3.6).
*stream_buffer* <size>|no::
Add a buffer to the btrfs send stream (locally, on uncompressed
data), with a maximum size of '<size>'. This can give a speed
improvement (measured up to 20%) on both local or remote
operations, but also increases system load. A suffix of "k", "m",
"g", or "%" can be added to '<size>' to denote kilobytes (*1024),
megabytes, gigabytes, or a percentage of total physical
memory. Defaults to ``no''.
+
--
If enabled, make sure that the "mbuffer" command (at least version
20180505) is available on the host running btrbk. As of btrbk-0.29.0,
mbuffer(1) is used for both 'rate_limit' and 'stream_buffer' options:
mbuffer [-m <stream_buffer>] [-r <rate_limit>]
Note that mbuffer(1) always reads defaults from "`/etc/mbuffer.rc"`
and "`~/.mbuffer.rc`".
Leave this option disabled if your main concern is a stable backup
process: while recent versions of mbuffer have proven reliable, it is
often desirable to keep things simple rather than adding an
additional, multi-threaded process to the command pipe.
--
*stream_buffer_remote* <size>|no::
Add a buffer on remote hosts (either source or target). Defaults
to ``no''.
+
--
Enable this if you prefer buffering on the remote side, or even on
both sides: reasons for this depend on available memory, disk and cpu
performance (btrfs send/receive, compression), as well as networking
constraints.
--
*rate_limit* <rate>|no::
Limit the read rate of the btrfs send stream to '<rate>' bytes per
second (locally, on uncompressed send stream). A suffix of "k",
"m", "g", or "t" can be added to denote kilobytes (*1024),
megabytes, and so on. Defaults to ``no''. Note that 'rate_limit'
implicitly adds a stream buffer (see 'stream_buffer' option
above).
*rate_limit_remote* <rate>|no::
Add rate limit on remote hosts (either source or target). Defaults
to ``no''. Note that it usually does not make much sense to enable
both 'rate_limit' and 'rate_limit_remote'.
=== System Options
*transaction_log* <file>|no::
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: "localtime type status
target_url source_url parent_url message".
*transaction_syslog* <facility>|no::
If set, all transactions (as described in 'transaction_log' above)
are logged to syslog. The program name used in the messages is
"btrbk". Accepted parameters for '<facility>': user, mail,
daemon, auth, lpr, news, cron, authpriv, local0..local7.
*lockfile* <file>|no::
Create lockfile <file> on startup; checks lockfile before running
any btrfs commands (using perl "flock"), and exits if the lock is
held by another btrbk instance. Ignored on dryrun ('-n',
'--dry-run'). See also '--lockfile' command-line option.
*backend* <backend>::
Backend filesystem utilities to be used for btrfs specific
operations. Available backends:
+
--
*btrfs-progs*::
Default backend, btrfs commands are called as specified in
btrfs(8) (e.g. "btrfs subvolume show").
*btrfs-progs-btrbk*::
btrfs commands are separated by a dash instead of a whitespace
(e.g. "btrfs-subvolume-show" instead of "btrfs subvolume
show"). Useful for setting suid or file capabilities (setcap) on
specific btrfs commands, as implemented in
<https://github.com/digint/btrfs-progs-btrbk>.
*btrfs-progs-sudo*::
btrfs commands are prefixed with "sudo -n" (e.g. "sudo -n btrfs
subvolume show" instead of "btrfs subvolume show"). Make sure to
have appropriate (root) permissions for the "btrfs" command groups
as well as the "readlink" and "test" commands in /etc/sudoers.
*btrfs-progs-doas*::
Similar to btrfs-progs-sudo, using prefix "doas -n".
If you want to set this option for local or remote hosts only, set
*backend_local* or *backend_remote* (e.g. "backend_remote
btrfs-progs-btrbk").
If you want to set this option for regular (non-root) user only, set
*backend_local_user*.
--
*compat* <compat-option>...::
Enable compatibility options. Available 'compat-option':
+
--
*busybox*::
Use busybox compatible commands, at the expense of slight overhead
while reading filesystem information.
*ignore_receive_errors* _*experimental*_::
Tell btrfs-receive(8) to not terminate on errors by setting
"--max-errors=0" option. Print warnings instead.
+
A known use case for this are target hosts lacking xattr support
(e.g. some Synology NAS), while the send-stream contains "lsetxattr"
commands. Another case is targets failing to set otime, complaining
with "ERROR: attribute 12 requested but not present".
+
Note that there is *no guarantee that backups created with this
option enabled can be restored at all*.
If you want to set this option for local or remote hosts only, set
*compat_local* or *compat_remote* (e.g. "compat_remote busybox").
--
*cache_dir* <directory>::
If set, cache extent maps for the "btrbk extents" command.
=== Btrfs Specific Options
*incremental_prefs* <list-spec>[:<amount>]...::
Specify the preferences to determine the best common (correlated)
parent and clone sources for incremental backups, by choosing from
predefined candidate lists.
+
--
The 'list-spec' defines from what candidate list the next
parent/clone-src should be appended to a result list; 'amount' defines
how many (e.g. "sro:1 sro:1" is identical to "sro:2"), or all if
omitted. Any candidate which is already in the results is dropped.
The resulting list of subvolumes is then used as parameters for the
btrfs-send(8) command: the first for "-p <parent>", all others for
"-c <clone-src>".
Available 'list-spec' (candidate lists = filtered subsets of
correlated subvolumes):
*sro*,*srn*:: All from 'snapshot_dir' matching 'snapshot_name', with
parent_uuid relationship, sorted by btrbk timestamp (o=older
n=newer).
*sao*,*san*:: All from 'snapshot_dir' matching 'snapshot_name', sorted
by btrbk timestamp (o=older n=newer).
*aro*,*arn*:: All from 'incremental_resolve', with parent_uuid
relationship, sorted by cgen (o=older n=newer).
Defaults to "sro:1 srn:1 sao:1 san:1 aro:1 arn:1". Note that for
most operations the default resolves a single parent, as there usually
are no newer snapshots, and all "sro:1 sao:1 aro:1" resolve to the
same snapshot.
Example: "defaults,sao,san,aro,arn" takes the defaults, and adds clone
sources for all (!) known candidates on the filesystem.
--
*incremental_clones* yes|no::
If enabled, btrbk adds "-c <clone-src>" to the btrfs-send(8)
command for all correlated subvolumes resolved by
'incremental_prefs'. If disabled, only "-p <parent>" is
used. Defaults to ``yes''.
*incremental_resolve* mountpoint|directory::
Specifies where to search for the best common parent for
incremental backups. If set to ``mountpoint'', use parents in the
filesystem tree below the mount point of the snapshot and target
directory. If set to ``directory'', use parents strictly below
snapshot/target directories. Set this to ``directory'' if you get
access problems (when not running btrbk as root). Defaults to
``mountpoint''.
*btrfs_commit_delete* yes|no::
If set, wait for the transaction commit at the end of each
snapshot or backup deletion (sets '--commit-each' option for
"btrfs subvolume delete"). Defaults to ``no''.
*send_protocol* <number>|no _*experimental*_::
Use btrfs send protocol version N. If enabled on 'target', btrbk
adds "--proto <number>" to the btrfs-send(8) command. Defaults to
``no'' (btrfs default).
*send_compressed_data* yes|no _*experimental*_::
Send data that is compressed on the filesystem directly without
decompressing it. This requires protocol version 2 or higher
(btrfs-progs >= 5.19), and implies "send_protocol 2". If enabled
on 'target', btrbk adds "--compressed-data" to the btrfs-send(8)
command. Defaults to ``no'' (btrfs default).
*snapshot_qgroup_destroy* yes|no _*experimental*_:: {blank}
*target_qgroup_destroy* yes|no _*experimental*_:: {blank}
*archive_qgroup_destroy* yes|no _*experimental*_::
Whenever a subvolume is deleted, also destroy corresponding
default qgroup "+0/<subvol-id>+". Only useful if you have enabled
btrfs quota support. See also:
<https://bugzilla.kernel.org/show_bug.cgi?id=91751>
=== Informative Options
*warn_unknown_targets* yes|no::
If set, prints a warning if btrbk encounters a target subvolume at
a unknown location (i.e. not following btrbk naming scheme, or
outside the target directory). Defaults to ``no''.
RETENTION POLICY
----------------
Retention policies are defined individually for snapshots, backups and
archives (summarized as "backups" in the following text), using a
combination of:
**_preserve_min* all|latest|no|<number>{h,d,w,m,y}::
Amount of time (duration) in which all backups are preserved.
**_preserve* no|<retention_policy>::
Schedule (single points in time) for which individual backups are
preserved.
Note that if "preserve_min" is set to ``all'' (the default), any
setting of "preserve" obviously has no effect.
The format for '<retention_policy>' is:
[<hourly>h] [<daily>d] [<weekly>w] [<monthly>m] [<yearly>y]
*hourly*::
Defines how many hours back hourly backups should be
preserved. The first backup of an hour is considered an hourly
backup.
*daily*::
Defines how many days back daily backups should be preserved. The
first backup of a day (starting at 'preserve_hour_of_day') is
considered a daily backup.
*weekly*::
Defines how many weeks back weekly backups should be
preserved. The first daily backup created at
'preserve_day_of_week' (or the first backup in this week if none
was made on the exact day) is considered as a weekly backup.
*monthly*::
Defines how many months back monthly backups should be
preserved. Every first weekly backup in a month is considered a
monthly backup.
*yearly*::
Defines for how many years back yearly backups should be
preserved. Every first monthly backup in a year is considered a
yearly backup.
Use an asterisk for ``all'' (e.g. "target_preserve 60d *m"
states: "preserve daily backups for 60 days back, and all monthly
backups").
Hint: Run btrbk with the '-S', '--print-schedule' option to get a
comprehensive output of the scheduler results.
=== Reference Time
The local time on the host running btrbk defines the reference time
for all date/time calculations, especially for "beginning of a day",
and as a consequence for the first daily, weekly, monthly or yearly
backups. The local time on remote hosts (ssh source/target) is never
used.
Unless "timestamp_format long-iso" is set, daily backups are preserved
at "preserve_hour_of_day" (defaults to midnight) of the respective
time zone (and not for "00:00 UTC", which would be "14:00" in
Honolulu). This becomes relevant for setups with multiple btrbk
instances, e.g. many snapshot-only instances (spread around the
world), and a fetch-only instance on the backup server.
Caveat:
* If "timestamp_format long-iso" is set, each btrbk instance on has a
different interpretation of "first in day". Make sure to run btrbk
with the same time zone on every host, e.g. by setting the TZ
environment variable (see tzset(3)).
TARGET TYPES
------------
*send-receive*::
Backup to a btrfs filesystem, using "btrfs send/receive". This is
the recommended (standard) target type. The '<target-directory>'
must be an absolute path and point to a subvolume or directory
within a btrfs file system. See btrfs-send(8), btrfs-receive(8).
*raw* _*experimental*_::
Backup to a raw (filesystem independent) file from the output of
btrfs-send(8), with optional compression and encryption.
+
--
Note that the target preserve mechanism is currently disabled for
incremental raw backups (btrbk does not delete any incremental raw
files)!
Raw backups consist of two files: the main data file containing the
btrfs send stream, and a sidecar file ".info" containing metadata:
<snapshot-name>.<timestamp>[_N].btrfs[.gz|.bz2|...][.gpg]
<snapshot-name>.<timestamp>[_N].btrfs[.gz|.bz2|...][.gpg].info
For 'incremental' backups ("incremental yes"), please note that:
* As soon as a single 'incremental' 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.
* There is currently no support for rotation of incremental backups:
if 'incremental' is set, a full backup must be triggered manually
from time to time in order to be able to delete old backups.
Additional options for raw targets:
*raw_target_compress* <compress_command>|no::
Compression algorithm to use for raw backup target. Supported
'<compress_command>': gzip, pigz, bzip2, pbzip2, bzip3, xz, lzo,
lz4, zstd.
*raw_target_compress_level* default|<number>::
Compression level for the specified <compress_command>.
*raw_target_compress_long* default|<number>::
Enable long distance matching for the specified
'<compress_command>'.
*raw_target_compress_threads* default|<number>::
Number of threads to use for <compress_command>.
*raw_target_split* <size>|no::
Split the raw backup file into pieces of size '<size>'.
*raw_target_block_size* <number>::
Block size to use for writing the raw backup file. Defaults to
``128K''.
*raw_target_encrypt* gpg|openssl_enc|no::
If enabled, encrypt the target raw file using gpg or openssl_enc.
Additional options for "raw_target_encrypt gpg":
*gpg_keyring* <file>::
Keyring to use for gpg, e.g. "`/etc/btrbk/gpg/pubring.kbx`".
*gpg_recipient* <name>...::
Encrypt for user id '<name>' (email address).
Additional options for "raw_target_encrypt openssl_enc" ('very
experimental'):
*openssl_ciphername*{nbsp}<name>::
Defaults to ``aes-256-cbc''.
*openssl_iv_size* <size-in-bytes>|no::
Depends on selected cipher.
*openssl_keyfile* <file>|no::
Point to a key file in hex (absolute path). Example key file
creation (256bit key):
+
------------
# dd if=/dev/urandom bs=1 count=32 \
| od -x -A n \
| tr -d "[:space:]" > /path/to/keyfile
------------
*kdf_backend* <file>|no::
KDF backend to be executed,
e.g. "`/usr/share/btrbk/scripts/kdf_pbkdf2.py`".
*kdf_keysize* <size-in-bytes>::
Defaults to ``32''.
*kdf_keygen* once|each::
Defaults to ``once''.
--
AVAILABILITY
------------
Please refer to the btrbk project page *<https://digint.ch/btrbk/>*
for further details.
SEE ALSO
--------
*btrbk*(1)
AUTHOR
------
Axel Burri <axel@tty0.ch>
Reference in New Issue View Git Blame Copy Permalink