Friday, October 05, 2007

Invalid extent entry

I recently bragged to somebody about OSX's geek friendly nature. Under the hood, it runs unix.

During my childhood I spent many long nights in the machine room rebuilding unix file systems using fsck. Crashed machines always resulted in file systems that needed some time of repairs. System admins learned the difference between the routine and the serious. More than once we were confronted with the inevitable 2:00AM question, "do I spend another several hours piecing together this file system, or cut my losses and restore yesterday morning's backup?"

Fsck was a powerful (and the only) tool for file system repairs. And the experienced admin could recover the most corrupted file systems if given enough time.

Fast forward 20 years: I'm attempting to upgrade my lovely wife's iBook to 10.4. But the upgrade is refusing to run due to a "disk error." I looked at the install log (which are conveniently made available by the installer app) and see a specific error Invalid extent entry. After a little poking around I realized that the error is coming from fsck, that it's a fairly minor error due to a corrupted directory, but that the only choices to repair are to format your disk or to buy a third party tool like DiskWarrior!

It seems that OSX's incarnation of unix isn't quite as rustic, or as "self service" as the unix of old. Apple's customer's expectations of ease of use must be evolving the platform into a PC with a really cool command line, rather than the hackers only system that was unix and is today linux.

Oh, and in case you're wondering, I bought DiskWarrior at CompUSA because the download version doesn't allow you to boot from CD (probably some licensing problem with Apple) and it made quick work of the directory error that was holding things up. A couple of hours of watching the barber pole and Monica's running Tiger..

2 Comments:

Blogger Sean said...

My dear Steve, you can fsck your filesystem in OS X. Just boot with Cmd-S. :-)

8:15 PM  
Blogger Steve said...

Yes, however, fsck can detect, but cannot repair this type of error. Thus my point that it has been demasculated in the past few years.

9:21 AM  

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