snbk — Command-line program to backup snapshots of snapper
Snbk is a command-line program to backup snapshot of snapper. It can transfer and delete backup snapshots on local and remote btrfs filesystems.
For each snapper config there can be several backup configs. Each backup config defines backups of the snapper snapshots at one location, either local or remote, see snapper-backup-configs(5) for possible settings.
Each snapshot has a status on the source and on the target. Possible values for the source are:
The snapshot is missing and thus considered obsolete on the target. It will be deleted on the target by the next delete command.
The snapshot is read-only.
The snapshot is read-write and thus cannot be backed-up.
Possible values for the target are:
The snapshot is missing. If the source snapshot is read-only it will be transferred to the target by the next transfer command.
The snapshot is valid. That implies it is read-only.
The snapshot is invalid. Either the received UUID is wrong or it is read-write. That can happen if the transfer was interrupted. The next transfer command will try to transfer the snapshot again.
-q, --quiet
Suppress normal output. Error messages will still be printed, though.
-v, --verbose
Increase verbosity.
--debug
Turn on debugging.
--utc
Display dates and times in UTC. By default, local time is used.
--iso
Display dates and times in ISO format. ISO format is always used for machine-readable outputs.
-t, --table-style style
Specifies table style. Table style is identified by an integer number.
--machine-readable format
Specifies a machine-readable output format. Possible options are csv and json.
--csvout
Sets CSV output format. See RFC 4180 for the details, except lines end with a LF, not CR+LF.
--jsonout
Sets JSON output format.
--separator character
Specifies the character separator for CSV output format.
--no-headers
Suppress headers for CSV output format.
-b, --backup-config name
Use specified configuration instead of all configurations.
--no-dbus
Operate without a DBus connection.
Use with caution.
--target-mode name
Only operate on backup configs with the specified target mode.
--automatic
Only operate on backup configs which have the automatic flag set.
--version
Print version and exit.
Snbk provides a number of commands. Each command accepts the options listed in the GLOBAL OPTIONS section. These options must be specified before the command name. In addition, many commands have specific arguments, which are listed in this section. These command-specific arguments must be specified after the name of the command.
help
Show short help text.
list-configs
List available configurations.
list (ls)
List snapshots.
transfer [number]
Transfer all missing snapshots or the specified snapshot to the target.
delete (remove|rm) [number]
Delete all obsolete snapshots or the specified snapshot from the target.
transfer-and-delete
Combines transfer and delete.
So far a restore has to be done manually. There are several methods to do a restore, e.g. the backup can be mounted and then copied or rsync can be used. Here we provide an example on how to use btrfs send and receive to restore a snapshot on the source system. In general using btrfs send and receive is a bit tricky.
When using target-mode local:
# mkdir /.snapshots/42
# cp /backups/root/42/info.xml /.snapshots/42/
# btrfs send /backups/root/42/snapshot | btrfs receive /.snapshots/42
When using target-mode ssh-push:
# mkdir /.snapshots/42
# scp backups.example.com:/backups/eberich/root/42/info.xml /.snapshots/42
# ssh backups.example.com btrfs send /backups/eberich/root/42/snapshot | btrfs receive /.snapshots/42
If the system was reinstalled it is unfortunately in general not possibly to simply use the restored snapshot as the new default snapshot since some files, e.g. /etc/fstab, likely need modifications. Also unfortunately for other subvolumes than root a rollback is not supported.
If there are snapshots on the source to speed up the operation you can also use the -p option for btrfs send.
The content of snapshots transferred must not be changed on the source system. Normally this is ensured since the snapshots are read-only. But it is possible to change snapshots to read-write. This can cause error during transfers in the future.