Backup block devices

Special files like block devices or pipes are by default stored by only the metadata of the special file like a device number. This allows to restore something like /dev on Unix platforms and to get the original state.

Sometimes, however, you want to backup the contents of block device, e.g. a snapshot of a disc. To do so, rustic supports the set-devid options. You can define it in the config file:

[[backup.snapshots]]
sources = ["/dev/my-blockdev"]
set-blockdev = "file"

or directly on the command line

rustic backup --set-blockdev=file /dev/my-blockdev

Note that for blockdevices, a fixed sized chunking with chunksize being a multiple of the block size is recommended as this speeds-up the backup from large single files and also good chunking points are typically on block boundaries for block devices. Fixed size chunking can be set e.g. during repository initalization, for example:

rustic init --set-chunker=fixed_size --set-chunk-size=1MiB