C-Command Software Forum

Consolidate Time Machine .sparsebundles?

I just found your app by searching ‘sparsebundle’ on Apple’s AppStore.

I am looking for a tool to solve a specific problem. Bear with me while I frame the scenario.

I use Time Machine ™ on a Time Capsule (TC) for my ongoing backups. Cognizant of the possibility of unit failure of the TC, theft, or a meteorite hitting my site, I also do a monthly backup of the TC itself. This has been done by procuring yet another USB hard drive (HDD), attaching it to the TC itself, and using AirPort utility to archive the TC’s internal Data partition to the USB HDD, which is then saved offsite. Each month, another HDD.

After several years of this process, I now have several dozen USB HDDs stored offsite, with all the hardware and management cost that this entails.

I recently learned a little bit about the internal structure of the .sparsebundle files created by TM. I am referring here to how they can be mounted on a device node in the (VFS? I’m not a BSD guy) filesystem, and can be browsed using finder as another mount under DEVICES. Further, I see that each incremental backup seems to consist of a folder labeled yyyy-mm-dd-mmhhss, which is in turn browsable.

This assumed knowledge leads me to believe that it should be possible to consolidate the data on all my offsite backup HDDs onto a single drive (space permitting). I am thinking specifically of mounting the oldest HDD and the next-oldest simultaneously, and copying the unique data (i.e. the yyyy-mm-dd-hhmmss folders not present on the older HDD) from the next-oldest to the oldest HDD. Then leaving the oldest HDD mounted, mount the next-next oldest, transferring its unique data. Then progressing through the sequence of HDDs in this manner.

When done, I would have a single HDD containing my entire TM history. I could then de-commission all the other HDDs, repurposing them for some other use.

This sounds simple in concept, though I can envision numerous gotchas that may require coding solutions.

So after all the above, my direct question cones down to this: Does your DropDMG utility support some or all of the above scenario?

DropDMG doesn’t really do any of this except for mounting the sparsebundle disk images. My guess is that this copying would not really work because, without the ability to intelligently create hard links the way Time Machine does, you would quickly fill up the drive that you are consolidating on. Also, I think it’s valuable to have several independent backups in case of drive failure or a copy error.

I think in your situation what I might do is use DropDMG to create compressed disk images of select dated Time Machine folders (say, one per month). This would save space (due to the compression) and also protect you via checksums so that if you ever have to restore you know your backup is good.