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germ
06-19-2006, 05:57 PM
I put a 300 GB ATA drive inside a PowerMac g4 and did a backup of the PowerMac's boot drive onto a sparseimage file on the 300 GB disk. I might have repeated the backup (with only changed files) a couple of times. I checked one time that the sparseimage would mount on the PowerMac G4.

Then, I took the 300 GB drive and put it into an external FireWire enclosure. My mac mini can now mount the 300 GB volume with no problem, but when I try to mount the sparseimage file, it fails with "no mountable file system found". Disk Utility reports an "invalid B-tree node size" and is unable to repair it because "the underlying task reported failure on exit".

DiskWarrior can re-create the directory, but cannot replace it. I think this is because it's a disk image.

So, I am stuck. This data was irreplaceable.

I thought that SuperDuper was reliable, and I was wrong. Using a sparseimage was probably a bad idea in the first place, as it cannot be easily repaired.

Any ideas?

dnanian
06-19-2006, 06:10 PM
SuperDuper! is reliable, germ, but in this case the problem is that the image was somehow corrupted at a low level. We don't operate at a low level -- so, this must have happened because something in the OS or drive failed. What that is, I'm not sure: I just don't have any information to work with.

Did you have any problems when you performed the operation, on the drive, ejecting, etc? Something must have happened to it. Perhaps it's the FireWire enclosure, since everything worked properly until you placed the drive into it?

germ
06-19-2006, 10:22 PM
Thanks for the fast reply.



Did you have any problems when you performed the operation, on the drive, ejecting, etc? Something must have happened to it. Perhaps it's the FireWire enclosure, since everything worked properly until you placed the drive into it?

Absolutely nothing happened. I am an experience mac user, and made sure to unmount the volume before removing the FireWire drive. The enclosure worked fine before and continues to work fine. The next logical step would be to remove the drive from the enclosure and connect it directly inside a PowerMac (unfortunately, I do not have such a machine now).

I feel though that this would not work.

Having the files in a sparseimage severely limits the file recovery options (i.e., DiskWarrior is useless). It seems to me that sparseimages are not reliable in OS X.

dnanian
06-19-2006, 10:27 PM
Then, it seems the problem might have been the controller, germ. Things were mounting and looking correct before you used the enclosure, so it seems that's what changed...

And, yes: as I discuss in the User's Guide, a sparse image is less reliable than writing directly to disk. It's why I suggest writing directly to the drive if possible... the less indirection, the better.

That said, I've found sparse images to be quite reliable in my experience. I copy to them multiple times a day, every day, and haven't had a problem.