larswik Posted January 18, 2008 Report Share Posted January 18, 2008 Hello, Retrospect is working great on my machine but I had a question. 4am I have a script launch that backs up everything that I have done or changed that day before. It launches fine and I have no problems except for the fact that the back up drive never seems to shrink in size when I toss things out. When I first started I had a 500 gig raid that had 370 gigs on it. My back up drive was about the same a few weeks ago. Now my Raid drive is only has a 329 gigs on it but my Back up drive is still at 370 gigs. I looked at the snap shot to see if the files that I trashed were still backup but they were gone from the snap shot that I looked at then I went to restore and select the files that I wanted. Why are the files gone from the backup drive but the file size is still just as big? is it not removing it from the back up as well? Thanks, -Lars Link to comment Share on other sites More sharing options...
rhwalker Posted January 18, 2008 Report Share Posted January 18, 2008 Quote: Why are the files gone from the backup drive but the file size is still just as big? is it not removing it from the back up as well? Because that's the way BACKUP works. It's a BACKUP so that you can go BACK to things that were there before if, for example, you happen to delete things by accident. You may not understand the Retrospect paradigm. Under the hood, it's like all other BACKUP programs, in that the first time, it writes out all files (a so-called "full" backup) and, in every successive BACKUP, it writes out changed/added files (a so-called "incremental" backup). Note that, in this scenario, nothing is ever deleted from the BACKUP. In a (patented) difference from other BACKUP programs, Retrospect also maintains a database of the state ("snapshot") of the source at the time of the backup. Because of the way that the BACKUP data set is written (full, then incrementals), this state (snapshot) really is a bunch of pointers back in to all the prior BACKUPs that were made, noting where each of the currently-present files are stored. It's a little more complicated than this, because additional metadata is stored (permissions, ownership, modification dates, etc.) for each file. Because of this structure, even though the user interface view shown by Retrospect is the most recent snapshot, you can also "add" prior snapshots to the interface view by having Retrospect re-analyze the data and figure out, by replaying the history of full, incremental, incremental, ... BACKUPs, what the snapshot state was at any prior point, so that you can restore a source to its prior state at any prior BACKUP time. Compared to other backup programs, Retrospect's strength is at the time of restore. Other backup programs, because they do not maintain this "snapshot" of the state of the source, require that you first restore the full backup and then every successive incremental so that you end up with (at least) the final files. It's harder to find the files to restore with other programs, and the restore takes longer. Again, note that there has been no deletion from the BACKUP set, even as files are deleted or changed. The BACKUP set grows unbounded as additional BACKUPs are made. The Windows version of Retrospect has a "grooming" feature that the Macintosh version does not have, in that a policy can be set so that only a limited set of snapshots are retained (e.g., the past five weeks, days, etc.), and Retrospect will warm over the backup set and delete files that are no longer needed for any retained snapshots. That, when it works (doesn't always - read the Windows forums here), allows the size of the backup set to be managed. Clear? Point being, backup is not maintaining a copy - it's maintaining a history. Russ Link to comment Share on other sites More sharing options...
larswik Posted January 18, 2008 Author Report Share Posted January 18, 2008 Thanks for the reply Russ. That is a truly unfortunate feature and no grooming feature on the Mac platform which would solve my problem. You understood my post and I understand what you are saying. I have a 500 gig raid and a 500 gig USB backup and an Exabyte tape drive for my deep archive. I remove them from my Raid for tape back up and it would have been nice for Retrospect to also see the file that have been removed, but I guess not on the Mac. I guess the only way around it is when the USB drive is full to delete the back up and start fresh again with a whole new backup. I hope they fix this BUG for the mac side so I can better use Retrospect for my needs. Thanks again Russ, I now see how the program works with regards to History Archiving vs. Backing up -Lars Link to comment Share on other sites More sharing options...
rhwalker Posted January 18, 2008 Report Share Posted January 18, 2008 Quote: I hope they fix this BUG for the mac side so I can better use Retrospect for my needs. It's not a bug, it's an integral part of the design. No substantive changes are able to be made to the current code base because it is written in CodeWarrior, which means that it can only generate PPC code that has to be emulated under Rosetta on Intel architectures. The only cure is to scrap the current code base and start over. There are signs that EMC may be on that path, but it's not a short path. I hope that the userbase remains to support such a solution by the time it arrives, if ever. Apple abandoned the PPC platform and migrated to an Intel architecture three years ago. It's long past time for software vendors to do so. Russ Link to comment Share on other sites More sharing options...
rhwalker Posted January 18, 2008 Report Share Posted January 18, 2008 Quote: I have a 500 gig raid and a 500 gig USB backup and an Exabyte tape drive for my deep archive. I remove them from my Raid for tape back up and it would have been nice for Retrospect to also see the file that have been removed, but I guess not on the Mac. Then consider an alternate strategy, more similar to what we do. You can use your Exabyte tape drive for "deep archive" as you call it, but also use the Exabyte for daily backup. Yes, the tape backup set will grow unbounded (periodically, start a new backup set). But that will give you your history. If you don't have an autoloader, I suggest that you get one. Exabyte has a range of products - we use their VXA-2 1x10 1u PacketLoader (SCSI). Then, with your USB "backup" disk drive, use a different technology (SuperDuper! or CarbonCopyCloner) to also clone/duplicate your RAID drive. We use a slightly different approach. In addition to our Exabyte tape backup, we use SoftRAID and form a RAID 1 mirror with two members: our Apple Hardware RAID (RAID 5 over 3 drives in our Xserve) and a big SCSI drive. Then we split the mirror, removing the SCSI drive from the mirror, giving an instantaneous perfect copy of the RAID without taking the server down. The mirror split allows us to go back to the previous day's state instantly, if needed, and the Exabyte tape backup allows us to retrieve files back to the epoch (1992). We never reuse tapes, just start a new backup set when the current tape set fills. It would be nice if Retrospect for Mac had Disk-to-Disk-to-Tape staging so that the backup window could be short and then the slower rollout to tape could happen during the day without disturbing users. Other Mac backup software has this, and Retrospect for Windows has it. I've stopped holding my breath (it's been 15 years that we have used the product, since Retrospect 2.0 on our long-retired ASIP server) for it to appear on the Mac. Hope this helps, Russ Link to comment Share on other sites More sharing options...
larswik Posted January 18, 2008 Author Report Share Posted January 18, 2008 Hey Russ, I knew it was not a bug that is why I put it in CAPS to voice a frustration. the Deep Archive are video projects that I will almost never visit again. I had a raid 1 with my 500 gig set up but it was not fast enough for some HD video and was getting dropped frames, which is why I switched to Raid 0 and the USB drive. I am not a huge company and I bought the new FireWire Exabyte drive for $1k so no autoloader. I don't want to put that much wear and tear on the Exabyte drive for nightly back ups. I could switch to Super Duper or CC for my back ups but the one thing I like about Retrospect is everything is in 1 file. This way there is no chance of me accidentally opening a file and modifying it from my backup drive in stead of my raid. I will more then likely use Retrospect for my tape drive and find some smarter up-to-date software for my day to day back ups. Or just trash the files and start over when the drive fills up. Thanks again for your help and clarity on the matter. -Lars Link to comment Share on other sites More sharing options...
CallMeDave Posted January 18, 2008 Report Share Posted January 18, 2008 Quote: I could switch to Super Duper or CC for my back ups but the one thing I like about Retrospect is everything is in 1 file. This way there is no chance of me accidentally opening a file and modifying it from my backup drive in stead of my raid. There are more benefits then this. For any program to DUPLICATE the contents of one volume to another, when that destination volume already has existing, unchanged files, the program must first compare each and every file on the source volume to each and every file on the destination volume to know what's old and what's new. In a Retrospect BACKUP, the specifics of the files that have already been copied are stored in the catalog file. So Retrospect need only compare the contents of the Source against a single file, the contents of which provide all the information necessary to keep track of what files are already in place. The cost is the need for additional space, while the benefit is faster operation and historical "Time Machine" style data management. Dave Link to comment Share on other sites More sharing options...
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