New Media chooses same tape number??

[jpreng]

Hi all - first time poster - hope I do it correctly....

 

We are trying to do a new backup scenario and running into a limitation (?) or issue. What we want to do is a full backup every friday of our Lan (all macs running 9.x) which is about 35GB and will fit onto one DLT8000 tape. Then do an incremental starting on Monday, going to thursday - again all will fit onto one tape. Then on friday, start over with a new set of tapes. So we can always have a full backup and a weeks worth of data on tape and off-site. We would *prefer* to have the Friday full and the weekley incremental in the same storage set so if we have to do a restore on say wednesday, all the info is in one storage set, rather than restoring the friday first, then the incrementals on top of it.

 

Therefore we have a new media script for Friday, a new media on Monday, and a normal for Tues - Thurs. The *glitch* we ran into was that on Monday, it wanted a blank tape to call it 1-<storageset>, even though Friday's tape already had that name. I was under the impression the new media option would simply force the use of the next tape in the storage set, and it would *know* what tapes already existed in the set. The reason for my wanting to do this is we can take the friday tape off-site on Monday, and we would *never* have to worry about the tape running out in the middle of the night since both the full and the 4 days of incrementals would each fit onto their own individual tape.

 

Is there a way to do this that we are missing? Please tell me if you need more info or if any of this is confusing. Thanks in advance for your time!!!

[mcswgn]

On Monday you don't want "New Media", you want "Skip". This will skip the rest of the current tape and continue the backup on a new tape. You may not always want "New Media" on Friday either. New Media restarts a backup set with the intention that the tape is to be archived and not used again. Most people don't want to send every tape off to permanent storage every time, so they set up a rotation of backup sets. Using a different one each week (StorageSet A, StorageSet B, ...), but eventually bringing them back for reuse. In that case, when you bring a tape back to reuse, you would not do a "New Media", you would do a "Recycle".

 

Quote:

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We would *prefer* to have the Friday full and the weekley incremental in the same storage set so if we have to do a restore on say wednesday, all the info is in one storage set, rather than restoring the friday first, then the incrementals on top of it.

 

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For Retrospect there is no such thing as "Full" vs "Incremental" backups. There are only files that have yet to be written to the storage set. All files are *always* in a single storage set, no matter how many pieces of media it spans (except to the extent that you create other, completely *independent* storage sets). Restores are never done in stages. When a restore is necessary you pick the date (snapshot) to which you want the machine restored and Retrospect prompts you for each of the needed tapes.

[jpreng]

Hi - thanks for the answer! But how do I do a "skip"? i don't see that option in the list with normal, recycle, or new media.

[mcswgn]

I've never tried to put it in a script, so maybe it's not possible. It can be done manually (at the same time you switch the tapes) by clicking on the Configure tab in the Retrospect window, then Backups Sets (or are they called Storage Sets there? The terminology used by Dantz has changed), double click on the current backup set, then the Options Tab, and finally the Action button. (That sounds a lot worse than it is.) There you will find radio buttons for: Normal, New Media, Recycle, and Skip.

 

You may also want to watch how much is on each tape by the end of a week in case it all might just fit on one tape. Obviously the most will be written the first night, but even over a week the additional volume for the later nights will typically be a fraction of the first one. I probably backup 75-80GB in my first go around (although for me the "first go around" takes a week as we have a very slow network) and it will take another 3-4 months before I've backed up another equal amount (which is when I recycle a backup set). You can monitor the amount of data on each member of a backup set by clicking on the Members tab in the backup set configuration window (instead of Options -> Action). When estimating how much space is left, don't be fooled by the usual capacity claims, though. Claims are always based on an assumed 2:1 compression ratio, but for our system I see a pretty consistent 4:3 ratio.