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davidflas · Jul 29, 2010, 06:54 PM

I am trying to help a co-worker with her iMac. It hangs at start up on the grey Apple logo screen with the spinning wheel below it. She cannot find the original software discs. I was able to get the iMac to start up with the disc from my mid 2009 MBP, but obviously I can't re-install the Mac OS from It. System profiler says that SMART status has been verified. When I run disk utility fails, saying that it is unable to repair the disc. Not sure what to do next...any suggestions?

davidflas · Jul 29, 2010, 07:08 PM

I tried re-formatting from my retail Snow Leopard disc. Disk Utility says the HD on the iMac has an invalid node structure and can't be repaired. It recommends backing up the HD and re-formatting. Is there any way to save the data?

indigoimac · Jul 29, 2010, 07:19 PM

Try booting it in target disk mode (press T on boot) then connect it via firewire to your machine (or another mac) ...it should mount the volume as an external drive... assuming there isn't something else wrong. But if it's popping up in Disk Utility enough for it to try to do something it may be accessible. All that said if you "tried to reformat" already that may have just made the situation that much worse making the volume unmountable. If that is the case the best bet is gonna be something like DiskWarrior to try and rebuild whatever got hosed and you might be able to salvage it. Sounds like either osx decided to corrupt itself or that drive is having problems in which case it needs to be replaced anyway (SMART is only valid when something catastrophic has happened in my experience and that doesn't happen too too often anymore)

davidflas · Jul 29, 2010, 07:40 PM

I can't try target mode at this point because I don't have a firewire 400 to 800 adaptor. I may have misspoke in my first post, I didn't try to reformat....I just tried to use the discs from my Mac to try to get to disk utility, not re-format. My co-worker claims that she was in the middle of trying to back up to an external HD when her iMac crashed. She has had some issues in the past when trying to upgrade to Snow Leopard. Are there any known issues with SL and this model of iMac? PS The HD in the iMac won't mount.

indigoimac · Jul 30, 2010, 09:00 AM

Originally Posted by davidflas

I can't try target mode at this point because I don't have a firewire 400 to 800 adaptor. I may have misspoke in my first post, I didn't try to reformat....I just tried to use the discs from my Mac to try to get to disk utility, not re-format. My co-worker claims that she was in the middle of trying to back up to an external HD when her iMac crashed. She has had some issues in the past when trying to upgrade to Snow Leopard. Are there any known issues with SL and this model of iMac? PS The HD in the iMac won't mount.

I've got that same model and have been running SL since it came out so no problems that I can report. Sounds to me like the HD has been having some issues for a while (or a fresh install was needed if you want to be optimistic)

When you say the HD won't mount -- do you mean the iMac won't boot? Or that even when you pull up something like Disk Utility it doesn't show up? Without target disk mode you're really limited because that's an easy way to circumvent the OS and establish if it is hardware or software. If the drive is still functional and only system files are corrupted the drive should still mount as the partition tables and all the stuff that establishes the data on the drive should still be there meaning at a minimum you can pull it off to another drive.

davidflas · Jul 31, 2010, 08:57 AM

I've gotten the iMac to work by connecting an external usb HD and booting from that. I'm running 10.5.8 without issues. When I boot the iMac I get a message saying that "Macintosh HD needs repairing and is being made available with limited functionality" or something like that. I'm beginning to think that all we're dealing with here is a botched install of SL. The woman I"m helping has a very limited understanding of how to use a computer. She's giving me her external HD, I'm going to back up her data, then reformat the internal drive on the iMac using a retail SL disc..hopefully that will help. I'm not sure why I stated that I tried to reformat the iMac HD in a previous post, I meant to that I was trying to repair the HD. Thanks for your help, its good to know that SL should run just fine on this computer.

indigoimac · Jul 31, 2010, 11:43 AM

Yeah -- something got corrupted. The method you suggest of pulling the stuff off and then doing a clean install should work fine.

Keep an eye on that drive though -- make sure you're confident that it's not the drive.

Also, yeah, Disk Util isn't that great at "repairing" things, except in very specific instances... DiskWarrior is kind of the next step for salvaging and usually takes care of it.

davidflas · Aug 7, 2010, 07:16 AM

Time to take this thread in a new direction. My coworker decided to order a new iMac and give this one to me. I replaced the HD in the iMac with a new one, closed the iMac up, installed Snow Leopard, ...and now the iMac works great except the airport card has a lot of trouble connecting to my wireless network. It sees it occasionally, but won't connect. Anybody who has been inside one of these iMacs have suggestions on what to check? I took the bezel off of the iMac and the antennas seem to be connected to the Airport Extreme card...did I put the EMI shield back in the wrong way...