Boot and Disk Utility problems

[Thrace]

I have a 2005 Intel iMac (1.88 gHz core 2 duo, I think) running 10.5.8, which up until a few days ago has performed stellarly. The problems began when the screen went black; I was out of the room when it happened and it was unresponsive when I returned, so I don't know if there were any associated error messages. After a hard shutdown (holding down power button), the computer did not boot up, instead staying on the grey screen with the apple icon and a perpetually spinning disk. Since then, I have discovered the following:

- Booting in Safe Mode doesn't work (I get an intermittent prohibitive sign in place of the apple icon and the spinning disk continues seemingly forever)

- Booting from the install DVD works, but Disk Utility reports that the HD cannot be unmounted whenever I try to run repairs.

- My attempts to verify the drive using Disk Utility result in the following output:

Verifying volume "Macintosh HD"
Performing live verification.
Checking Journaled HFS Plus volume.
Checking Extents Overflow file.
Checking Catalog file.
Invalid record count
Volume check failed.
Error: Filesystem verify or repair failed.
​

- After zapping the NVRAM and PRAM per http://support.apple.com/kb/TS1892?viewlocale=en_US, the HD is not listed as an option by "Startup Disk..." from the Utilities dropdown on the install DVD. Similarly, holding down the option key during startup to force a boot disk selection yields the install DVD as the only option.

[Edit] Prior to zapping the NVRAM and PRAM, there was no startup chime when I turned on the power, but there has been every time since. Not sure if that's significant.

- I haven't done any fiddling with permissions (at least, not intentionally), but the buttons for both verification and repair of permissions in Disk Utility are greyed out.


That about sums it up. I would like to try booting in Verbose mode, but since it no longer seems to be recognizing the HD as a viable boot disk, I haven't bothered. Also, the error message for the failed attempt to unmount the disk for repairs comes with a reminder that I should close all open files and applications on that disk and try again, which seems ludicrous since I can't even boot from it. Does anyone know of a workaround?

Thanks in advance for any help...

 

[teapot]

Hi
It seems you have come across all your failings in one foul swoop. All I can suggest is to perform a clean install of your system. That will allow you to replace any problem files to be reintroduced one by one. Unless you have your entire system backed up with time machine.
Best of luck

 

[Thrace]

I've been moving and as a result haven't had the chance to do much mucking around until tonight. That being said, there have been some interesting developments:

After rebooting from the install DVD and again failing to repair or verify, I tried once more to unmount the HD. Surprise: it worked! However, I have no idea what changed to allow this to happen, and neither verify nor repair gave me anything new afterwards.

So this time I rebooted into single-user mode. After much mucking around, I was able to identify my hard drive's disk ID and start fsck via the following:

/sbin/fsck_hfs -y /dev/disk0s2
​

It ran through the same output I provided above, but instead of halting after a failed Catalog check, it informed me that it was rebuilding my B-tree and proceeded to output a lot of what looks like this:

disk0s2: 0xe0030005 (UNDEFINED).
Invalid record count
(4, 103)
​

Every few minutes or so it spits out that first line followed by either "Invalid record count" or "Invalid node structure" and another set of numbers. It hasn't covered every intervening address (I'm assuming these are memory locations), but is now somewhere in the 3000s.

At this point I am going to let it do it's thing while I try and get some sleep (emphasis on try: it's about 90 here with humidity in the 60s). Hopefully when I wake up my screen will not have melted and I'll --maybe-- be able to boot from my HD again. Or at least start another round of fsck.