Faulbaer's Schlafmulde :: english :: technology :: data rescue saved the day
2013.12.18, 00:45

data rescue saved the day

when I came back from london last month I noticed my mac behaving a little different from how I remembered it to. it wouldn't open disk images, it seemed to have stopped serving torrents although the internet connection was working and it wouldn't open files or applications. soon enough just about two hours later it just died on me. after a not so quick reboot I noticed the drobo wasn't coming up. I tried to check it with the disk utility but it wouldn't mount and the disk utility blabbered something about a directory being something with something blah foobar. I had been pondering to buy disk warrior on several occasions so I just went ahead and got me a copy. for $99 it turned out to be able to make the drobo accessible again but it wouldn't repair it because of some rather undefined problems that also made the scanning take ages - well today I think disk warrior is priced far to high for what it does.

next I had to buy some large usb-drives to recover as much data as I could. it took me over a week to suck all the data from the drobo and after some more crashes, reboots and several severe nightmares later my recovery work was done and I had all my encrypted sparsebundles back - just one wouldn't mount. the one that wouldn't mount had a virtual size of 4 tb and a real size of 550 gb and as it turned out it wouldn't mount because just about ten band-files worth 256 mb were missing from the band directory in the sparsebundle package.

this has happened before and would happen again - but not to me it hadn't.

after some googling around and reading this and that knowledge base discussion I was ready to give up. apples mount process just wouldn't accept a broken sparsebundle with missing band-files - it didn't matter if those were even used or necessary - it just wouldn't mount it - basta.

then I googled a little more, finding the article "repairing corrupt / damaged sparsebundle" pointing to this article "repair / rebuild damaged .sparsebundle" which finally gave me the solution: data rescue 2 which had been updated to version 3 by the time and which proved to be the helpful companion I needed to get my files back. it crashed, too but after just two more days it had recovered all the files I needed from the broken sparsebundle into a new one. the final clue suggested to mount the broken sparsebundle using the -shadow-option of the hdiutil. this then presented a readable and writable block-device for prosoft's data rescue (link removed on prosoft's request) to work with in expert mode.

although the 3d interface of the tool is a little childish and very much unnecessary the tool works great and is great value for the $99 I had to pay for it. it can't do wonders but for what it's worth it recovered all the data I needed and that's worth a lot to me.

a few final words about the sparsebundle file format: it sucks! apple should have the responsable team whipped until they get their heads out their asses and fix it.

- it's so fault intolerant it feels like it's from the eighties - all the journaling in the world can't help a sparsebundle if it's lacking band-files or if band-files and plist-file mismatch - dudes, get it fixed!

- there is no hashed directory-structure for the bands there are just millions of band-files sitting flat in the band directory waiting for accidents to happen

- there is virtually no usable documentation anywhere to be found on this sparsebundle packaging format - how open is that?

Faulbaer (and why does mac os x go insane beyond ten or more attached sparsebundles?)

 
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