vol-sync is a simple rsync like tool but especially made for disk volumes.

Rsync was designed for transferring files and requires some special command-line options to work well with disk volumes.

vol-sync aims to transfer full and/or incremental disk volumes using a SSH tunnel from a local host to a remote host. To achieve this the client on the local host connects to the remote host and runs an instance of vol-sync there. These two instances communicate with each other and use MD5 hashes to determine chunks of data which differ between the local host and target host. If the hashes do not match the chunk is updated on the target side and otherwise skipped.

Just like rsync vol-sync needs to be installed on the local and remote host. Their versions are checked during initialisation and the transfer is aborted if they mismatch.

vol-sync checks if the target volume is large enough for the source volume to fit in. If the target volume is large one could use tools like "resize2fs" to make use of the available space.

vol-sync does not ask for confirmation when writing to a target volume! Thus there is a risk for loosing data if the target volume was chosen incorrectly!

Do not use the "-s" switch manually, this switch is for internal use only!

For simplicity build and install the Debian package as follows:

$ dpkg-buildpackage -b
$ sudo dpkg -i ../vol-sync_*.deb

vol-sync shall be used as following:

USAGE:  vol-sync [OPTIONS] [SOURCE TARGET]

Mandatory arguments in client mode:
  SOURCE      Source volume (device) on the local host
  TARGET      Target volume (device) on the remote host,
              given as [USER@]HOST:VOLUME

Optional arguments:
  -e COMMAND  SSH command (default: ssh)
  -h          Show this usage information
  -i SECONDS  Print status every x seconds (default: 15; 0=off)
  -r PATH     Absolute path to the vol-sync executable on the remote machine
              (default: none to use the search path)
  -s TARGET   Run in server mode and use the given target volume (device)
              (internally used when connecting to a remote machine)
  -v          Verify chunks after write (default: off)

Version information:
  vol-sync 0.0.1

$ vol-sync /dev/sdb1 user@remote-host:/dev/sdd4

vol-sync tries to connect to "remote-host" and authenticates as user "user", then the block device /dev/sdb1 from the local host is synchronized to /dev/sdd4 on the remote host.

$ vol-sync -e 'ssh -p 2222' -r /opt/vol-sync/bin /dev/vg-a/vol1 user@remote-host:/dev/vg-b/vol2

vol-sync tries to connect to "remote-host" port 2222 and authenticates as user "user". On the remote host vol-sync is launched from /opt/vol-sync/bin/vol-sync, then the block device /dev/vg-a/vol1 from the local host is synchronized to /dev/vg-b/vol2 on the remote host.