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My iMac has been running horrendously slow the past couple days, so I booted into the Snow Leopard CD and ran a disk repair and a permissions repair. Now I can't get past the spinner. It's been going for about 4 hours now with no shows of progress. Does any body have any ideas on what else I can try (I already tried doing the repairs again) or is there any way I can debug this?

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Have you tried booting in Safe Mode? – Ryan Sharp Jan 27 '11 at 23:35

There's a free app called AppleJack that's good for ths kind of thing. If you don't have that, Apple Hardware Test may help.

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Thanks @nathan, I'll check those out – wajiw Jan 27 '11 at 23:06
+1 AHT. Hold D while booting your iMac to get into that. – Harv Jan 28 '11 at 0:46

Try Verbose Boot - Command-V while starting, it will show you what the systme is doing as it starts up instead of a pretty gray face. If you get anything like "disk0s2: I/O Error" you're looking at a failing hard drive. Go to the nearest Genius Bar or other AASP. If you get hung up with some other errors, try re-installing the system from the Snow Leopard DVD.

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When you ran a disk verify (which, IIRC, you must do before you can run a disk repair,) what were the errors that came up? You may be looking at a dying hard-drive. Try to use the iMac as little as possible until we (or someone at Apple/with an Apple certification) can help you figure out what's going on.

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If it'll boot into single-user mode (hold Cmd-S while booting) try repairing it with fsck (filesystem consistency check and interactive repair) -- "help fsck" when you get the prompt. Work carefully; you'll have root permissions!

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This is what Disk Utility does. Shouldn't make any difference doing this or using the GUI utility on the install disc. – Nathan Greenstein Jan 27 '11 at 23:47
Most advice I read concerning fsck suggests that it's a poor idea to run it on a mounted file system because the FS can change underneath it, and that it won't fix any errors in that case. Thus, my recommendation for running it in single-user mode. See , for example; or Google 'fsck multi-user' for others. – JRobert Mar 12 '11 at 17:15
That's why I said 'on the install disc'. That way, you've booted with the CD and the HDD's fs isn't in the way. – Nathan Greenstein Mar 12 '11 at 17:17

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