Guest Posted April 3, 2003 Report Share Posted April 3, 2003 I just purchased and received 2 new tape drives to replace existing failling drives. A VXA-1 drive is now on an ASIP 6 server with Retrospect 4.3. The other is a VXA Autopak 1x10 with a VXA-2 drive on a dedicated backup server running mac os x 10.2.4 and Retrospect 5.x. On both machines, Retrospect thinks the tape capacity is only 2 GB. While, this is not really a huge issue and I know I can go in and tell it the real theoretical capacity, I was wondering if anyone knew why this was happening. Thanks. -Gary Link to comment Share on other sites More sharing options...
Mayoff Posted April 3, 2003 Report Share Posted April 3, 2003 These items from the tape capacity FAQ should be helpful: http://www.dantz.com/index.php3?SCREEN=kbase&ACTION=KBASE&id=27418 http://www.dantz.com/index.php3?SCREEN=kbase&ACTION=KBASE&id=27411 http://www.dantz.com/index.php3?SCREEN=kbase&ACTION=KBASE&id=27419 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...
Guest Posted April 3, 2003 Report Share Posted April 3, 2003 Thanks Mayoff, but I already know that information. My question is why does one server think that I can get 2 GB on a tape that can hold 12-24GB and another server think that I can get 2 GB on a tape that can hold 80-160 GB. The Dantz knowledgebase even suggests that Retrospect should think that it can hold more. http://www.dantz.com/index.php3?SCREEN=kbase&ACTION=KBASE&id=27673 So, does anyone have any idea why retrospect is guessing so wrong on these VXA-1 and VXA-2 drives? Link to comment Share on other sites More sharing options...
ghoffman Posted April 3, 2003 Report Share Posted April 3, 2003 Quote: So, does anyone have any idea why retrospect is guessing so wrong on these VXA-1 and VXA-2 drives? I don't think Retrospect is even guessing. I think it is just assuming a default (low) value when it cannot determine the true value. The real mystery is why it cannot determine the true value. The information is there for the asking from the VAX-1 drive. Retrospect did report correct values for my old Travan drive, as an example, but that was a few years ago now. But a worse failing is that Retrospect does not report the amount used (or remaining) on a tape. That information is also available and would be even more valuable than reporting tape size (which we know from looking at the tape label). Only Dantz knows why the VXA tape drives are not fully supported. Glenn Link to comment Share on other sites More sharing options...
Mayoff Posted April 3, 2003 Report Share Posted April 3, 2003 Actually tape drives do NOT report the amount of space available. A tape drive does not know, as explained in the media capacity FAQ. Tape capacity changes depending on speed of data transfer, compression, media length, etc. http://www.dantz.com/index.php3?SCREEN=kbase&ACTION=KBASE&id=27365 Retrospect does show you how much is on the tape, by going to Configure>Backup Sets>properties>members. Link to comment Share on other sites More sharing options...
ghoffman Posted April 4, 2003 Report Share Posted April 4, 2003 Quote: Actually tape drives do NOT report the amount of space available. A tape drive does not know, as explained in the media capacity FAQ. Tape capacity changes depending on speed of data transfer, compression, media length, etc. Well, my VXA-1 tape drive allows me to determine the remaining (native) capacity of a tape. I am able to obtain that information using the vendor provided VXATool. The procedure is quite cumbersome and therefore not really suitable for production use, but it can be done quite reliably. If the procedure were integrated into Retrospect (using commands to directly access the tape drive), I believe all the awkwardness could be removed. I will admit this is not the same as the numbers Retrospect reports, as compression is not included, but for my shop I know the approximate ratio of Retrospect capacity to native capacity, which does account for both compression and data transfer speed. And as I indicated before, the tape drive will report media length. That the native capacity is not the same as the Retrospect capacity does not detract from its value in managing tapes. I would guess that not all tape drives provide a way to determine tape capacity and remaining capacity. From Dantz' point of view, reporting the information may be a low priority because of this. But it sure would be convenient in my operation if it were implemented. And, if Dantz gets interested in improving the interface to the VXA drives, they might also consider reporting some of the other information available, such as hours since last cleaning. And major errors encountered during a session. And the compression ratio as seen by the drive. Link to comment Share on other sites More sharing options...
j0nharris Posted May 15, 2003 Report Share Posted May 15, 2003 My problem is similar... . My travan firewire drive is 20Gb, but Retrospect consistently thinks it is full at just over 9Gb. Hopefully, manually setting the capcity will let me get more on the tape Link to comment Share on other sites More sharing options...
AmyJ Posted May 15, 2003 Report Share Posted May 15, 2003 Changing the estimated capacity will not affect the actual capacity of the tape - the estimate is for display only. Retrospect will stream data to the drive until the drive indicates the tape is full. If you are experiencing capacity issues, please review the following Tape Capacity FAQ for causes and solutions: 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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