Also remember that you will never get 40G of data on the 20G tape using compression. Binary files never compress 50% and actually compress very
Neither of those statements are strictly true. I've seen ratios of 10:1 or better. It all depends on the nature of the data that you are backing up. Now, I don't know if hardware compression can do quite that well, but gzip certainly can, and bzip is even better (although *far* more expensive).
RE: Hardware compression. I have some highly compressable data I backup. Sometimes the tape drive will just stop spinning for 30 seconds or more at a time. When I look to verify nothing is broken I see that data is pumping out at 20 MB/sec or more, so it is the highly compressible nature of the data that is allowing the tape drive to basically idle. Greg -- Greg Freemyer The Norcross Group Forensics for the 21st Century