SNBK(8)

NAME
snbk - Command-line program to backup snapshots of snapper

SYNOPSIS

snbk [--global-opts] command [command-arguments]

snbk {--help}

DESCRIPTION

Snbk is a command-line program to backup snapshot of snapper. It can transfer and delete backup snapshots on local and remote btrfs filesystems.

CONCEPTS

  Backup Configurations

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.

  Snapshot Statuses

Each snapshot has a status on the source and on the target. Possible values for the source are:

(empty)
    The snapshot is missing and thus considered obsolete on the target. It will be deleted on the target by the next delete command.

read-only
    The snapshot is read-only.

read-write
    The snapshot is read-write and thus cannot be backed-up.

Possible values for the target are:

(empty)
    The snapshot is missing. If the source snapshot is read-only it will be transferred to the target by the next transfer command.

valid
    The snapshot is valid. That implies it is read-only.

invalid
    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.

legacy
    The snapshot is valid, but the source snapshot's metadata has changed since the transfer. The next transfer command will update the snapshot's metadata on the target.

  Visualization

Snbk provides a visualize command for producing graphs in Graphviz DOT format for visualization purposes. Currently, producing tree diagrams for snapshots on both the source and the target is supported. The command output can be piped to the Graphviz tools to generate an image.

Here is an example of producing a tree diagram for snapshots on the source side with the 'root' backup config:

    # snbk -b root visualize source-tree | dot -T png -o root-source-tree.png

In the tree diagram for snapshots, a node has the properties virtual and valid. A virtual node means the corresponding Btrfs subvolume is not managed by a Snapper snapshot. A valid node means the node exists on both the source and target sides, and can be used as a valid Btrfs send parent to reduce disk usage during snapshot transfer or restoration. The root node of the diagram is a specialized virtual node, which is not a Btrfs subvolume, representing the Btrfs filesystem on the source or target.

GLOBAL OPTIONS

-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. For some commands the CSV output contains more information than the default table output. See RFC 4180[1] for the details, except lines end with a LF, not CR+LF.

--jsonout
    Sets JSON output format. For some commands the JSON output contains more information than the default table output.

--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.

COMMANDS

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.

restore [number]
    Restore all missing snapshots or the specified snapshot back to the source. A backup config must be specified to run this command. A restart of the `snapperd` service is required to make the restored snapshots visible immediately.

delete (remove|rm) [number]
    Delete all obsolete snapshots or the specified snapshot from the target.

transfer-and-delete
    Combines transfer and delete.

visualize [options] mode
    Produce a Graphviz graph with the specified mode. See Visualization for more detail.

    -r, --rankdir rankdir
        The 'rankdir' diagram attribute of Graphviz. Defaults to 'LR'.

    source-tree
        Produce a tree diagram of the snapshots on the source.

    target-tree
        Produce a tree diagram of the snapshots on the target.

RESTORE

Snapshots can be restored using the restore command. There are more 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 manually 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.

NOTES

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.

PERMISSIONS

Since the target-mode ssh-push needs root permissions on the target it is recommended to use a dedicated machine or container as a target.

FILES

/etc/snapper/backup-configs
    Directory containing configuration files.

EXIT STATUS

Normally the exit status is 0. If an error occurred the exit status is 1.

HOMEPAGE

http://snapper.io/

AUTHORS

Arvin Schnell <aschnell@suse.com>

SEE ALSO

snapper-backup-configs(5), snapper(8), btrfs-send(8), btrfs-receive(8) rsync(1), sshfs(1)

NOTES

1.  RFC 4180
    https://tools.ietf.org/html/rfc4180