Directory damage and fallout -- looking for root cause

Question

One of the G5s (2x 2.7GHz, 4.5 GB RAM, 250 GB HD) I support at work started exhibiting erratic behavior yesterday (spinning ball, slow app launch, general weirdness) and I told the user to reboot. He did, and the grey pinwheel screen came up and it sat there spinning for a while and then went wind-tunnel with black screen.
I powered it back on and went into single-user mode and did fsck -fy and got a host of errors. Not thinking it wouldn't fix things, I don't remember what the initial errors were, but there were a lot of them. Missing files maybe?
Anyhow, it couldn't repair everything. The errors I then got were:
Incorrect number of thread records (4, 228)
and
Invalid volume file count
I booted with TechTool 4.x and it found errors as well but could not repair. I then bought DiskWarrior and booted up another Mac and plugged the G5 in via firewire disk mode. I rebuild the directory and rebooted the G5 into single user mode and fsck gave me a clean bill of health.
I rebooted again and it passed through the grey screen and "hung" on the blue screen prior to login for about 30 mins before I lost patience and rebooted in verbose mode.
In verbose mode, everything seemed to go well until I got the following message every three seconds...
...waiting for IFC
At that point, I left it to do its thing and came back this morning to the login window.
I then rebooted the machine again and it "hung" on the blue screen again.
Right now I am imaging the internal drive over to another drive. I am just going to rebuild the machine now, but what I really want to know is what is this IFC service that it was waiting for?
(Unfortunately the rebuild will take a while since it has both Adobe CS2 AND Final Cut Pro -- two long installs that require multiple DVD swaps)
--Mike

Answer 1

Michael,
Disk repair utilities, when they work, will return your file system to a "consistent state," but they cannot restore data that may have been lost as a result of the disk error. In other words, even after a successful repair, you may still have damaged files.
If the damaged files happen to be critical system files, the machine "won't go." Period.
The original cause could be one or more of several things. If the user that "rebooted" the machine had to perform a forced shutdown, doing so would only have aggravated the issue, causing further errors and damage. The original cause could have been a bad block on the drive, or it could simply have been a "tired" file system.
If you want to get ahead of the game somewhat, I would recommend that you "zero" the drive (with the drive selected in Disk Utility, not the "volume" on the drive). This will map out any potential bad blocks, thereby eliminating the possible need to go through this again in the near future.
Also, be aware that any "image" of the volume in question will, itself, remain damaged. I would recommend that you attempt to recover only user data from this backup; do not attempt to "restore" it using Disk Utility.
Scott