How do I go about making a low level copy?
dd bs=16M if=/dev/md0 of=/path/to/file
where /dev/md0 is the raid array node, and /path/to/file can be a disk or partition node, or a file (on a volume big enough). Make sure the if (InputFile) and of (OutputFile) are right. Dd will without asking overwrite your precious data if you copy in the wrong direction.
Because this is Linux, you are free to pipe it everywhere. For instance:
dd bs=16M if=/dev/md0 | gzip >/path/to/zipped/disk
will write the data to a compressed file.
dd bs=16M if=/dev/md0 | ssh user@nas "dd bs=16M of=/path/to/file"
will write the image to a file on a remote NAS, through ssh. Of course this will take a lot of time. (It will take a lot of time anyway). As the data is encrypted, you might have a higher throughput if you compress it first. (Encryption is expensive):
dd bs=16M if=/dev/md0 | gzip | ssh user@nas "cat | gzip -d | dd bs=16M of=/path/to/file"
There are two pieces of software called R Studio. The one I'm looking at is this one: http://www.r-studio.com/
Ah. Indeed I was looking to the other piece. According to that website the tool doesn't support xfs, so I think it's useless for you.