Comment Re: I'm still wondering (Score 1) 205
You need to make a clone of a snapshot. Then, you write that to tape, then you need to make at least md5sums of the disk image or of each file on the clone, read the tape you just wrote and compute checksums of the tape as well, then finally compare the checksums.
That's always what I did when using tapes and that's still what I do with usb connected hard drives I use nowadays instead for critical stuff on top of what I described above.
I have had and I still get regular but very occasional checksum failures comparing. You can't just write to tape and consider it a valid backup without comparing with the original before putting it away and moving it to a different location. When I get a checksum failure, I run the test again to make sure I get the same exact two different checksums again to insure the problem doesn't come from another hardware component like memory scsi/sata/usb controller, bad cable etc. etc.