On 5/23/05, Susanne Hemker <[EMAIL PROTECTED]> wrote: > Hi all, > I am looking for a new tape drive for backups and couldn't find any > good reviews online. Could anyone suggest a good drive for a regular > backup of a ~800GB partition? Up to now we had DLT drive using 80GB > tapes, but we are looking for a large capacity drive. Since I have no > experience with LTO drives any hints in that area would be really > appreciated. Or any suggestions on smaller capacity drives using an > autoloader. > Thanks for your help > Susanne >
For anything that big, I assume you are primarily looking at SDLT, LTO2, AIT (or SAIT). I'm not as current with tape drives as I used to be, but I know a couple of years ago, HP was recommending the LTO technology because of its ability to slow down. That can make your backup run a lot faster becuase it can reduce the amount of shoe-shining that the tape drive does. I don't know if any of the other drives technologies have added that capability or not. ==== Why slowing down can help. Assume you have a LTO-2 drive that can run at 30 MB/sec of compressed data to tape speed. Assuming 2x compression, you need to feed that drive 60 MB/sec of uncompressed data. HP recommended that you have a disk-subsystem that has the ability to achieve 3x the tape speed to ensure you had enough data to stay in the streaming mode of the tape, so now you need a 180 MB/sec disk subsystem. That is a lot of disk-subsystem speed. (Note that 180 MB is not out of the raw device, but out of the backup software which can be way slower than the disk itself.) So a simple disk speed test with "tar cf /dev/null ." can tell you how many MB/sec your disk subsystem can produce. Most systems have a hard time keeping up with the high-speed tape drives available. The LTO-1 drives from HP had the ability to slow down to as slow as half speed, and I believe all manufacturer LTO-2 drives have the ability to slow down. This means that if your disk subsystem is just a little too slow to keep the tape running at full speed, the tape motor just slows down a little. Other technologies used to kick into the ultra-slow shoe-shining mode. HTH Greg -- Greg Freemyer The Norcross Group Forensics for the 21st Century _______________________________________________ rdiff-backup-users mailing list at [email protected] http://lists.nongnu.org/mailman/listinfo/rdiff-backup-users Wiki URL: http://rdiff-backup.solutionsfirst.com.au/index.php/RdiffBackupWiki
