IMac Hard Drive failure

Question

Okay, so....last night my 27" iMac completely locked up as I tried to open Safari. It wouldn't accept any commands and I ended up powering it down via the power button on the back of the computer. I waited a few minutes and powered it back up and it stayed on the grey Apple screen with the gear grinding away for a good 10 minutes or more before allowing me to log in. I get in and attempt to open my mail and it hangs again so I power it down and restart again. This time, on the grey screen I get a status bar that never gets beyond 10% and never goes away. I shut down again and reset the PRAM....same thing, only now the status bar will go away after awhile (never gets more full than 10%) but I can never get beyond the grey screen. My next step was to dust off my OS X disk and boot from there (needed to use a wired keyboard as the wireless wouldn't connect, which I assume was because of the PRAM reset). When I first used the disk utility I Verified the disk and got back an "invalid node structure" error and then proceed to repair the disk. Took all of about 2 minutes before I got the message, "Disk Utility can't repair this Disk. Back up as many of your files as possible, reformat the disk, and restore your backed-up files."
Not willing to admit defeat I tried again, this time with a different error message, "Invalid Key Length" with the same ending....cannot repair. What are my options? I, of course, have not backed up in recent memory (re: EVER) so is all my info lost? Can I use my macbook pro to try and pull info off the iMac's HDD? I can't get the iMac to boot up past the disk utility. Will a reformat even fix my problem or am I going to need a new HDD?
Any advice or information will be greatly appreciated. Thanks.

Answer 1

Is there anyway to tell if this is a physical problem with the HDD or just a logic problem that a reformat will fix?
It is a physical problem with the drive, or with your Mac. If the SMART status shown in Disk Utility is anything other than "Verified," then it's certainly the drive. If the status is "Verified," it may still be the drive that's at fault, but you can't rule out a logic board fault.
You need to understand something about Disk Warrior. It's often touted in these forums as a maintenance tool, which it is not. It's a recovery tool with only one legitimate use: to recover data from a damaged HFS volume that Disk Utility can't repair, and for which there are no backups, or inadequate backups. That seems to be the situation you're in. Disk Warrior may enable you to recover some or all of the data from your drive, but if so, that doesn't mean everything is fine. You must still replace the drive, unless of course it turns out that your logic board is defective, but that's much less likely.
Once you've used Disk Warrior to recover your data, you should never need it again, because you're never going to get caught without a backup again.
There is not a shred of independent evidence that Disk Warrior's "defragmentation" of volume directories has any effect on performance. Apparently the vendor used to make that claim, but has abandoned it as the nonsense it was. In any case, you can get exactly the same effect by erasing the volume and restoring it from backup, probably in less time, and without spending $100.