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Strategy for taking tapes home every friday


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Thoroughly confused on this for some reason, I'm sure I'm just not thinking about it correcty.


My client, running version 6 would like to tape the Raid attached to their xserve.   They have two sets of tapes for their library each with 6 tapes and 1 cleaning tape.  They want to take tapes offsite each friday.  The have 2 sets of tapes.


So, I set up one backup set with M-Th as normal and Fri as recycle.  I told them to swap out the tapes on Friday morning.  That night the full runs on the new set and the following M-Th gets all the changed data.  The cycle repeats next Friday.


Last Friday the Full ran no problem, but tonight (Monday) the Normal backup stopped, looking for a tape name that does not exist .  I thought Retrospect would erase the tapes as necessary? 


Maybe I need two backup sets?

Does the client need to erase the tapes after loading the new set on Friday?





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Thanks very much for your reply.  Here is what I have now:





My concern is that the Friday full will run fine, but Monday will ask again for new media because it will see files on the tapes? 


This is what it was doing when I just had the ONE backup set:




and here are the tapes in the library:




Somehwere on those tapes is last Friday's Recycle/Full backup



Thanks again

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  • 2 weeks later...

Hello again - so it seems that I have something wrong in my script setup.  The Friday recyces labels all the tapes, and then does a Full.  However, the Saturday scheduled Normal yields this:




Here is the schedule:




My hope was that the scheduled backup would just copy files to wherever they needed to go - not sure why it is looking for a "7"

Thanks for any help.

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Hmm.. that sure would seem like the obvious answer - I'll check into that.


These are LTO3 tapes, I'm using hardware compression, but perhaps this is not working.


The Friday full ran and completed, backing up approx 2.7T


I'm going to turn on software compression for tonight and see what happens, but I'm pretty sure it's going to fail because:



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I don't think you can turn off hardware compression. At least it's turned on by default and it's hard to turn off.

Since the tapes hold 400GB of (native) data you already have compression on. Software compression is for disk media sets.


The compressed capacity of the tapes depends on two things: How "compressable" the data is and how fast it reaches the tape drive.


Many file types today is already compressed: Audio, video and images to start with. Then PDF files and word processing documents are often compressed. Files that are already compressed can't be compressed more. What is easiest to compress is pure text files.


If data isn't fed fast enough to the tape drive, blank (useless) blocks are added to the tapes while waiting for more data. This is much better (for many reasons) than having to stop the tape motion, reverse the tape a bit and start the tape again when data has arrived.

Many small files are slower than fewer large files (for the same amount of bytes).

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