I’ve been using sparsebundles for >10 years, and notably I have a large encrypted sparsebundle (in HFS+ format) in my main storage. I back it up regularly to external drives using rsync.
Problem 1:
For a few years (and so a few OS versions ago), I’ve noticed that not manually unmounting the sparsebundle before shutting down my Mac leads to weird problems:
- When my Mac next starts, the Finder hangs for a long time.
- When I next shut down my Mac, it also hangs for a long time with a blank screen before powering off.
- The problems tend to linger until I mount and unmount the sparsebundle again.
- If I back up the sparsebundle while my Mac is in this weird state, the backup is corrupt. However, I have always been able to mount the original sparsebundle again.
I find this weird, as in my understanding, a Unix machine is meant to properly umount all mounted volumes when shutting down. I don’t recall this was happening >5 years ago.
Problem 2:
I recently tried opening a backup of this sparsebundle from 10 years ago. It mounts fine, and I can read the contents. But after a while, the contents of some directories starts to disappear. No error message appears in the Finder, but using ls in the terminal returns I/O errors. At that point, properly unmounting the sparsebundle fails and I have to force unmount it. Then it is corrupt and I cannot mount it again.
I have tried to repair it to no avail, using:
hdiutil attach -nomount -noverify -noautofsck my_back_up.sparsebundle
fsck_hfs -drfy /dev/disk...
Note: the I/O errors are not caused by my external backup drive failing, as I have copied the sparsebundle from the external drive to my main storage before attempting to mount it.
I’m not even sure these two problems are related…
