philx509 Posted December 10, 2003 Report Share Posted December 10, 2003 I use Retrospect 6.0 for Windows Professional. My question concerns the amount of "overhead" that Retrospect uses on a backup job. Ive been backing up to tape a LOT of zip files, mp3s, etc., and other files that can't be compressed further. My drive is an Exabyte 8720 (internal version) on SCSI-160. No problems there. Doing all these backups, I consistently get only 4.4 - 4.6 GB of files on one 112m tape. Never 4.9 or 5.0. If I use a 160 m tape, I get about 6.5 - 6.7 GB. This is a local backup, streaming data at 50+ MB/second, so I don't think I'm getting buffer underruns. What is happening here? Link to comment Share on other sites More sharing options...
Mayoff Posted December 10, 2003 Report Share Posted December 10, 2003 Please see the media capacity FAQ http://www.dantz.com/index.php3?SCREEN=common_questions_detail&ACTION=COMMON_QUESTIONS_DETAIL&id=49 Link to comment Share on other sites More sharing options...
philx509 Posted December 11, 2003 Author Report Share Posted December 11, 2003 Quote: Mayoff said: Please see the media capacity FAQ http://www.dantz.com/index.php3?SCREEN=common_questions_detail&ACTION=COMMON_QUESTIONS_DETAIL&id=49 Thanks. I've gone through the FAQ, but that doesn't tell me why Retrospect identifies at 112 m Exa tape as 4.3 GB, when the rated capacity is 5.0 GB. Is this based on my historical usage, or does this include a "fudge factor" to account for lost capacity? Also, is there a lot of overhead for each file stored on tape, in effect a file "header" or "trailer." philx509 Link to comment Share on other sites More sharing options...
Mayoff Posted December 11, 2003 Report Share Posted December 11, 2003 Actually the FAQ does say: http://www.dantz.com/index.php3?SCREEN=kbase&ACTION=KBASE&id=27409 http://www.dantz.com/index.php3?SCREEN=kbase&ACTION=KBASE&id=27410 http://www.dantz.com/index.php3?SCREEN=kbase&ACTION=KBASE&id=27411 http://www.dantz.com/index.php3?SCREEN=kbase&ACTION=KBASE&id=27418 http://www.dantz.com/index.php3?SCREEN=kbase&ACTION=KBASE&id=27365 Link to comment Share on other sites More sharing options...
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