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cheese2 06-17-2006 04:19 AM

Advice on 2-stage backup to offsite storage.
I am looking for some advice on setting up a second-stage backup to offsite storage. The first stage consists of SuperDuper smart-updating a sparse image stored on a file server down the hall every 24 hours. This is the easy part - works great, auto-mounts, really fast. Nice.

Where I am running into trouble is how do I get the contents of that disk image from my local server to a remote server I have access to. I was originally planning to use Retrospect for this because I need to keep 30 days worth of revisions and (correct me if I'm wrong) SuperDuper always overwrites older versions of a file with the latest. However, Retrospect wants to re-back up the entire image file each time SD updates one little file on it, so I end up with 30 copies of everything, not just the files that have been modified. This is a massive waste of storage space, not to mention it takes days to transfer the image over the slow WAN connection.

If I use SuperDuper for the second stage then I can get the smart update to just take the modified files, but then I dont get my 30 revisions unless I make 30 images on the remote server and back up to a different one each day, and as I said earlier, I just dont have that kind of storage space.

I cant have SD make a second backup directly to the offsite server because there are firewall & changing ip address issues.

Does anyone have any suggestions?


dnanian 06-17-2006 08:50 AM

Sorry, cheese2 -- without creating the copies, you can't currently get SuperDuper! to store the revisions. This is something you'll need to use a different program to do.

If you want to use Retrospect for the 2nd stage, you could have it back up the *contents* of the image, rather the image. In other words, do it while the image is mounted.

Hope that helps!

edoates 06-17-2006 12:20 PM

Sounds like another "vote" for an enhancement suggestion I made via email.

Note that Retrospect can do what you want, but I despise the recovery procedure: it seems to take forever to reconstruct the directories so you can pick out a file (or files), and their scheduling was iffy with each new release of OS X. I used it until I discovered the elegant simplicity of SuperDuper for us mere mortal users.

To me, recovery of files or entire drives is the most important feature of any "backup" program. With SD it is so easy: mount the backup image and copy a file, just like normal.

But incremental difference sets would be a nice, new feature if it can be incorporated without complicating the full backup simplicity, and if an elegant method for using the difference sets, both for single file and full disk restoration can be invented.


cheese2 06-17-2006 01:57 PM

Thanks guys.

I despise Retrospect but the 30 revisions thing is not negotiable (I'm lucky it's not 60+ actually) This may be geting off topic a little but do you know if the retrospect client will auto-mount a disk image for backup the way SD does? I have never tried it, but my feeling is that only the main application can do this, and in my case its running on the offsite server not the onsite server where the images are.

I guess there are two things that could help out here. One is if SD could back up to a network share directly instead of an image on a share. Then, Retrospect client could access the files individually without needing anything to be mounted first.

The other approach would be to have SD be able to back up to a set of images: a master containing the full original backup and subsequent "revision" images containing just the files that have changed since the previous backup. In a perfect world, I could even pre-specify how many "revision" images were in the set and the oldest would auto-expire. The contents of the expired image would then be re-copied to the newest image if they were still present on the system being backed up, thus preventing my backup storage being filled with old deleted data. I can see how this would make restoring an entire volume more complicated, but SD would already know which image the most recent revision of each file is on because it put them there in the first place. Some sort of index file would probably need to be saved with the image set.

That is something I know Retrospect (theres that word again) cant do. At least not to anything other than tape (yuck!) and I would be willing to pay good money for software that can. Maybe it time for SuperDuper Enterprise Edition? :D

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