Keith Bierman's Weblog

Tuesday August 28, 2007

When good files go bad...

My current (and past to be candid) laptop of choice is a  Mac.  Laptops being easily stolen, an encryption technology like Apple's FileVault really is a must. But what happens when  Something Bad(tm)  happens during shutdown? Well, the  image can become corrupt and then opening it is... well impossible. 

Or so everyone told me. Google helped a bit., if I had kept backups of the * sparse image itself,  I might have been able to use this technique.

Not being one to give up easily, I copied the sparse image to  another machine and started experimenting. having had good results from DataRescue in the past, I tried it. But as their  support organization confirmed, they do  can do nothignng for sparse images.

Diskwarrior could, but not so much with the version I had. So time to upgrade. Much to my annoyance, in the laptop itself the application bailed with a numeric error message. However,  working on the desktop  copy it ran flawlessly and restored the sparse image. It was then a simple matter to delete  the version on the laptop and copy it over.

Several lessons:

1. Always make sure there is a second account on the laptop (good hygene suggests  making it be the adminstrative account. But at least having a second account ensures a way forward ;>). 
2. Backups of course; but there's almost always some window of  vulenerability where the backup isn't current. So keep current on your restoration/hacking options ;> Alsoft only offered the upgrade  via CD, so by not having updated aggressively I cost myself a week of data outage.
   
3. Things which aren't really secret, put them in the /Users/Shared area. That way they don't  take up space in the  sparse image, and are there post data  disaster.

I still enjoy the strange looks I get running Solaris in full screen mode in coffee shops (via VMware's Fusion). Of course that requires an Intel based Mac.