Lion (Mac OS X 10.7): Tip to minimize volume ejection bug

Posted by Pierre Igot in: Macintosh
July 13th, 2012 • 10:15 am

A while ago, I wrote a post about a number of annoying bugs that I have been experiencing in Mac OS X 10.7 (Lion). For the most part, these bugs are unfortunately still there, so I have had to learn to live with them.

There is one particular bug, however, for which I have found, not a solution, but a way to significantly reduce the number of occurrences. The bug involves my scheduled SuperDuper! backups, which normally take place during the night. As far as I can tell, the backups themselves work fine, but at the very last step, when it comes to ejecting the volumes (two sparse disk images and one hard drive volume) on which the backups are stored, something goes wrong. Lion fails to eject the volumes and then sometimes, all kinds of seemingly unrelated running processes start running at 100% CPU for no reason. I also get something like this happening in my Finder sidebar:

I have had extensive exchanges with the SuperDuper! developer and, unfortunately, we have come to the conclusion that the problem is most definitely a bug in Lion itself, which only Apple can fix. (The developer mentioned something about the diskarbitration daemon. I am afraid that’s all I know about it. This daemon is a root-owned process that cannot be quit, and it does not have CPU peaks when the bug occurs, so I don’t know if it’s actually involved.)

However, since this bug is rather annoying (CPU cores running at full capacity for extended periods cause my machine to heat up and, undoubtedly, my power bill to go up as well), I have been toying with various strategies to try and mitigate the problem.

First, I found that quitting BinaryAge’s TotalFinder Finder extension seemed to help avoid the problem. But after a few days I still ended up having a recurrence of the bug, even with TotalFinder not running. There was definitely an overall decrease in the number of occurrences, however.

Then I started getting in the habit of quitting the Finder itself altogether every night before going to bed. (You can easily add a “Quit Finder” command with various third-party utilities, or simply quit the Finder process in Activity Viewer.) This helped reduce the frequency even further.

I still get the bug from time to time, but we are down from something like every other day to something like every other week, which is obviously much better. (I also occasionally get what seems to be a partial manifestation of the bug, where in the morning I find that the Finder has somehow launched by itself, and some of the backup volumes are not ejected, and there are some weird background processes going on, such an mds process or some abnormal peaks in the Dock process CPU usage.)

I have no idea why quitting the Finder helps minimize the problem. This bug is obviously a bit complex, and that inevitably makes it a low priority for Apple. So any strategy that can help reduce the number of occurrences is useful and is likely to remain so for many more months. (I somehow doubt that the problem will be fixed in Mountain Lion.) I still have to live with the bug, but at least not on an almost-daily basis. If you are experiencing a similar bug (I haven’t heard from anyone else at this point), this might be a useful tip.

Comments are closed.