Full / Differential back ups

[retro]

Hello,

 

If I want to deliver a new tape to a VXA drive on tuesday, have a full back up run each tuesday night and differential run wed, thurs, fri, sat, sun and monday; then change the tape again on tuesday, how do I put this in the script?

 

-or-

 

If I leave the drive on default to run a back up each night and change the tapes, will a full back up run on a new tape? or does the retrospect software pull the information from what was backed up last from a log file on the hard drive an only add the differential info onto the new tape?

 

It appears that I have to pick all full or all differential. I want to have a full back up once a week, differential for the rest of the week and take the tape off-site.

 

Any suggestions on how I can do this?

 

Thanks!!

 

[mcswgn]

First, construct your script so that its hours of operation are something like 7pm to 7am every night with a repeat interval of 12 hrs and design it to use several backup sets (maybe Week1, Week2, Week3). Then have a blank tape for each of these backup sets. When you start, none of the backup sets will have any tapes associated to them. So to get started with Week1, do an Immediate Backup during the day on Tuesday (of something fast) to backup set Week1--using the blank tape you want for Week1. That tape is now a member of the Week1 backup set. Just leave the tape in the drive and, with no other intervention on your part, the software will do exactly what you want. The first night it will backup all files, since it has not previously backed anything up. The next night the 12 hr repeat interval will have elapsed and so it will start right at 7pm to go through the list again--this time only writing changed files. (This is Retrospect's standard behavior. It doesn't write files to tape that are already there. Hence, the effect is like a differential backup. However, the concept of Full vs Differential doesn't really apply to Retrospect. On every backup it records the complete status of the disk and can restore the disk to that state at a later time without having to restore in stages the way you would for a typical Full + Differentials method.)

 

When the next Tuesday rolls around, pop the Week1 tape out, stick in the blank tape for Week2 and again do an Immediate Backup (of something small) now to backup set Week2. Again leave the tape for the rest of the week. Keep repeating until you have gone through all of your backup sets once and are ready to start over. Now you need to decide whether you want to archive a given tape or reuse the tape. Either way, during the day on the Tuesday when you are going to be restarting the cycle, from the Retrospect window click on Configure -> Backup Sets, select the backup set you want to restart that night, and click Configure. Opps, and now without the software open in front of me, I can't remember the names of the tabs in this window. One of them allows you to select a media action (look at the manual). If you want to archive the current tape, select New Media. This will modify the name of the backup set (Week1 -> Week1 [001]) and allow you to put the old tape aside and use a new blank tape. If you want to reuse the tape (which is the most common), select Recycle. This will delete the current catalog for that backup set and leave it ready to reuse the current tape. (You do not need to erase the tape first.)

 

In theory, it should not be necessary to do the Immediate Backup step now as you start to repeat your cycle. The reason is that Retrospect will always write to the backup set that was used least recently if given a choice. Therefore, if all the other backup sets have data in them and only this one backup set has been reset, then when the script starts Retrospect will decide on its own that the proper backup set to be writing to (even though it has a blank tape in the drive) is the reset one and it will take that tape and associate it to the set you want. HOWEVER, if there are any other backup sets floating around or other scripts that could run, this will almost certainly get screwed up. I think it is good practice to always take the reponsibility on yourself to tie the tape to the set you want by doing that Immediate Backup. Then there is no chance for confusion.

 

One other point--Do NOT let the script do the resetting of the backup set for you (which is the default if you let Retrospect write the script). This is an action that cannot be undone and, in the case of a Recycle, causes a loss of data. (You are throwing away all the files and catalogs for that backup set before reusing it.) Making a mistake can be costly and it should not be entrusted to an automated system. Of course, you also have to make sure you selected the set you intended when you reset the media, but at least if you make a mistake you only have to kick yourself :-)