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Relationship between snapshots and grooming

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Hi all,


Could someone explain the relationship between snapshots and grooming? I need to free up more space in a storage set than grooming will free. If I forget all the snapshots from old clients will the next grooming run delete their data?


I know that I could transfer to a new storage set but that would require a TB of spare room I don't have.


What happened to me was I started deploying the client via GPO and Retrospect sees the newly deployed/updated client as a different client. Maybe because I am using certificates now. I think that is leading to data being copied a second time.





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A snapshot is an accumulated view, from the initial backup and subsequent incrementals, of the complete state of your files at the time of your backup. You can always (assuming that your backup set is readable) recreate snapshots ("rebuild catalog") from the backup set in order to do a restore, but it might take hours.


When you "groom", you remove files from the backup set that are not present in most recent snapshots. In other words, you remove older versions of files and files that have been deleted. Once the files are groomed out, you will not be able to restore them. Whether or not a grooming deletes files depends on how much you choose to save, and which files are needed to support the saved snapshots. If, for example, a file of a particular version was present in two snapshots, only one copy of the file will remain in the backup set, but the data for the snapshots (an index, if you will, of the backup set at a particular time, accumulated from daily incrementals, etc.) will remain.


There are two parts to the backup, namely, the catalog (index of incrementals and snapshots) and the backup itself (the files).





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So if I delete snapshots more will be groomed out since the files will not be needed to support the snapshots?


Perhaps. A counterexample where this might not be true would be if you did two backups, one right after another, with no intervening file changes or deletions. In that case, there would be the same set of files supporting both snapshots. Deleting one snapshot would not cause any files to be groomed out.


But I think you have the picture.



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  • 2 weeks later...

How do I forget multiple snapshots at once? It would be nice to be able to tag the snapshots I want/dont-want and then do a mass forget and then a Groom to clear out the space.


Instead, I am forced to Groom to the last 1 or 2 snapshots, which means I am forced to forget the older snapshots I want to keep.


Of course, the alternative is to click "Forget" on a snapshot, wait 5 minutes, and then repeat for each snapshot. Bad idea when there is about 20 to forget. Time is money!




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