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Tapes not fully used

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I have a tape library (Sony AIT 5) with 3 tapes forming 1 media set.

For some reason the second tape is in use while there is still room on the first one.

tape 1: used 468GB free 306GB, total 775GB.

 

Any idea why R8 switched to the second tape?

Any idea how R8 found a total of 775GB per AIT5 tape (400GB native, 1040GB compressed) ?

 

Software compression is not activated since I have the hardware compression enabled.

 

thanks

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This may or may not be a bug. No one has a clue what Retrospect is trying to do because there is no manual. But see a discussion of this issue in the following thread (the interesting part starts in the middle, where this link leads):

Tape member usage

 

Russ

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I have always wondered why I lose over 230GB of storage off of each LTO4 tape. I'm dealing with an issue where my library drops offline during backup operations and when it does, my LTO4 tapes store around 984GB, if the script works normally I can expect only 754GB per tape. Since my 6.2TB backup typically uses 8 tapes I'm losing over 1.6TB of tape capacity to 'overhead'.

 

Maybe EMC has stock in the magnetic tape supply vendors. ;)

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If the library is dropping offline, that's something to investigate. Retrospect will declare a tape member as unusable if it encounters errors during the backup to that tape, and move to the next member.

 

There has been some SCSI voodoo reported in some of the other threads here, with EMC support suggesting that the drive and library be at one's complement SCSI IDs (2 and 5). To my way of thinking, that would point to crosstalk in the LVD lines, or a blown LVD driver or receiver (giving 1/2 the noise immunity), causing noise on one line to affect others. By using one's complement SCSI IDs, causing all ID bits to switch together, might be a workaround for some other underlying issue...

 

I'd investigate the library dropping offline. Perhaps there are some extraneous SCSI Bus resets being caused by Retrospect 8. Saw a similar thing years ago with Retrospect 6, causing a system disk (a RAID 1 mirror of the boot and swap volume) to drop transfer complete interrupts once every few weeks, causing the system to hang (waiting on a paging interrupt that never came). Cure was to put the tape and library on their own SCSI channel. Perhaps this is similar. If so, it's very hard to track down. Been there, done that.

 

Russ

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Library dropping off-line aside, are you at least getting the uncompressed capacities from the tapes?

 

Using Retrospect 6, with an LTO-3 tape library, only using hardware compression, I was getting anywhere from 380 to 450GB on the 400/800 tapes being used.

 

Unfortunately, I haven't yet been able to get Retrospect 8 to successfully use our old LTO-3 tape library, but now it has died and I need to replace it, so I'm hoping it will work reliably with a new LTO-4 tape library, and at least provide 800GB per tape.

 

Any news on Library connection issues? I'm concerned about upgrading without hearing better news on tape library usage, but I also know that folks won't be posting good news, only when things don't work. ;-)

 

Best of luck.

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Any news on Library connection issues? I'm concerned about upgrading without hearing better news on tape library usage, but I also know that folks won't be posting good news, only when things don't work. ;-)

Well, things aren't going to get better until a bugfix release happens, and that's some unknown number of months out. See:

Next Retrospect 8 bugfix release might be out this quarter

 

Russ

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We have a similar problem with Retrospect 8:

- MacPro Intel with OS X Server 10.5

- ATTO ExpressPCI UL5D SCSI

- Sony AIT-5 External SCSI Drive, 400 GB (native) 1.04 TB (compressed)

 

Retrospect only writes a few GB of data on a new tape and then asks for a new tape. As we can read a lot of similar problems in this forum and questions to the retrospect support remain unanswered, I hope there will be a bugfix available shortly.

 

Does anybody know Bru Backup from tolisgroup? Probably it would be a better choice and therefore I will test this software the next days.

 

Thank you.

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