Invalid B-tree node size. Bad Hard disk?

Question

Invalid B-tree node size. Bad Hard disk?

I've got a 1.42 G4 Mac mini that was starting to lock up fairly soon after booting. I would get the spinning beach ball right after starting Safari. I though it might be the hard drive, so I booted with the Tiger dvd, and ran the Verify Disk from the Disk Utility. Everything seemed to check out so I tried to boot again, with no luck. I also ran the Hardware Test that came with the machine, which also checked out ok. Suddenly, my startup disk has disappearded and I get the flashing Question mark when I boot. So here's what I've done since:

- Reset PRAM
- Run the Hardware Test... everything checks out.
- boot with Tiger DVD, run Disk Utility, and Verify Disk: I get a message that says "Invalid B-tree node size" and "Error: The underlying task reported failure on exit"

Any Ideas?

Thanks!

Mac mini G4 - 1.42Gz Mac OS X (10.4.8) 512Mb RAM, 80Gb Hard Disk

Posted on Oct 22, 2006 11:22 AM

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Answer 1

Best reply

Douglas McLaughlin

Level 9

63,786 points

Oct 22, 2006 11:31 AM in response to Brad Montgomery

Did you try to "repair disk" instead of just verify? It's probably not a hardware problem with your hard drive, but there is a problem with the file directory structure of your hard drive (a software issue). The Disk Utility can help with many small file directory problems, but can't always fix more complicated trouble. If the Disk Utility can't "repair disk" on your drive, you might consider purchasing a more sophisticated file directory repair utility, like . It can often repair problems like yours better than Apple's Disk Utility.

-Doug

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Answer 2

Oct 22, 2006 12:53 PM in response to Douglas McLaughlin

Thanks Doug,
And yes, I did try the Repair option in Disk utility, and I also got a similar error.

I've also tried running fsck on /dev/disk0s3 from a terminal and I get the folling error from that:

BAD SUPER BLOCK: MAGIC NUMBER WRONG

I answered yes to the "LOOK FOR ALTERNATE SUPERBLOCKS?" but that failed as well, and I'm not sure where to go from there.

Mac mini G4 - 1.42Gz Mac OS X (10.4.8)

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Answer 3

BGreg

Level 6

17,552 points

Oct 22, 2006 3:34 PM in response to Brad Montgomery

I'm not sure where to go from there.

As Doug mentioned, Diskwarrior is a good repair tool which has recovered disks for many people, sounds like it might be time to consider it. Another alternative, assuming your disk is already backed up (or if you don't need to keep whatever you have on the drive), erase the mini hard drive and zero out the disk data, and start again.

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Answer 4

Oct 22, 2006 6:35 PM in response to Brad Montgomery

BGreg may be correct. It might be time to consider a repair utility besides Apple's free Disk Utility. I did a search for "BAD SUPER BLOCK" and couldn't find a reference to it before 2003. Apple's only Knowledge Base Article says it's only for Mac OS X 10.1.x Server and earlier.

If you have a file directory error that the Disk Warrior can't replace, you have two options. Purchase another, third party disk utility or erase and re-install. An "archive and install" won't replace the errors.

-Doug

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Answer 5

Oct 22, 2006 6:55 PM in response to Douglas McLaughlin

Thanks to both of you. I'm going to do a little research, and see if Disk Warrior will fix this problem. Unfortunately, there's still some data on the disk that I would like to recover, so I'm not ready to zero it just yet.

I did discover that you can find a list of the available superblocks using 'newfs -N' from Terminal. I had read in other places that you could use fsck -b and supply another superblock... but this didn't work for me.

I'll post information about my luck with Disk Warrior.

Mac mini G4 - 1.42Gz Mac OS X (10.4.8)

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Answer 6

Oct 22, 2006 7:09 PM in response to Brad Montgomery

The one time I've ever had to deal with a bad/alternate super block (and this was three years ago, at least), I believe the location of the alternate block was 32. But, I can't even find the instructions I used three years ago to find out how to format that in the command line.

Do you have another Mac with FireWire nearby? If so, you may be able to startup your Mac mini in FireWire Target Disk Mode and plug it into the other Mac to use it like a FireWire hard drive. You could backup some of your files to the other Mac or to CDs or DVDs using the other Mac.

-Doug

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Answer 7

Oct 22, 2006 7:13 PM in response to Douglas McLaughlin

From what I've read, 32 is always the "next" superblock. You could run

fsck -b 32 /dev/whatever

to run the system check...

Unfortunatley, the mini is the only mac I own 😟
Maybe it's time for a new one!

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Answer 8

Oct 31, 2006 4:38 AM in response to Douglas McLaughlin

It took me a while, but here's how the problem was solved:

1. I connected an external Fireware hard drive, and used it to install OS X.
2. I bough Disk Warrior and ran it on my Internal Harddrive. I let it rebuild the directory, and I'm back in business!

Thanks!

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Answer 9

Oct 31, 2006 11:18 AM in response to Brad Montgomery

Thanks for posting back. I'm glad you're back up and running.

-Doug

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