Capacity on VXA-1 drive

[msteele]

Retrospect 5.0.x running on a PowerMac 7600 connected to SCSI VXA-1 drive (several other OS X clients connected but this question doesn't apply to them). PowerMac 7600 running OS 9.

 

 

 

PM 7600 has 1 18 gig drive and 2 9 gig drives, one is a hand me down with nothing on it. Total capacity to backup this single machine is < 30 gigs. It should fit on one of the VXA-1 33 gig tapes, with compression it should hold it twice. In reality I get what appears to be reverse compression - that is about 15 gigs per tape. The backup completes one of the 9 gig drives (that isn't full) and about one quarter of the 18 gig when it runs out of tape and needs a new one.

 

 

 

I'm pretty sure that when I was running 4.3 I could backup this machine and several of the clients before I needed to swap tapes. I could get an entire backup on two tapes, now with 5 I need at least 4 but I have not doubled the total byte count.

 

 

 

I can I determine how much data is being put on one tape? How can I be assured that hardware compression is working?

 

 

 

Thanks,

 

-Mark

[AmyJ]

Check out these great Knowledgebase entries on Tape Capacity:

 

 

 

www.dantz.com/index.php3?SCREEN=knowledgebase_article&id=914

 

www.dantz.com/index.php3?SCREEN=knowledgebase_article&id=530

 

 

 

In reply to:

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I can I determine how much data is being put on one tape? How can I be assured that hardware compression is working?

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Go to Configure > Backup Sets > Properties > Members Tab. You will see how much data is on each tape.

 

 

 

To check hardware compression, make a new backup set _without_ hardware compression . This option can only be set during the backup set creation. Do a new backup of your source with software data compression enabled. This is set in the options for your backup. Make a second new backup set _with_ hardware compression enabled. Backup the same source. Compare the amount of data on the members.