Repair disk from single user mode (fsck fails)

bootfscksnow leopard

Earlier today my 2009 iMac emitted I/O errors trying to copy files. So I ran disk utility, verify disk to see if anything was amiss. It was. But as it's my startup disk I couldn't repair it, so I tried safe mode. Safe mode worked the very first time, but when I rebooted it shows the progress bar filling up, before halting. Every time I turn it on now, the same progress bar then crash happens. Booting in verbose mode reveals fsck is failing with signal 8.

Using single-user mode, as that's as far as I'm aware the only way I can get any access to the system, I've been running fsck_hfs. However, it always fails. Below is the output from fsck_hfs -d /dev/disk0s2.

** /dev/rdisk0s2
        Using cacheBlockSize=32K cacheTotalBlock=65536 cacheSize=2097152K.
** Root file system
   Executing fsck_hfs (version diskdev_cmds-491.6~3).
** Verifying volume when it is mounted with write access.
** Checking Journaled HFT Plus volume.
** Checking extents overflow file.
** Checking catalog file.
   Missing thread record (id = 9931104)
   Missing thread record (id = 16434146)
   Missing thread record (id = 19370458)
disk0s2: I/O error
hfs_swap_BTNode: offsets 10 and 11 out of order (0x0000, 0x0000)
   Invalid node structure
(4, 115897)
** The volume Macintosh HD could not be verified completely.
        volume check failed with error 7
        volume type is pure HFS+
        primary MDB is at block 0 0x00
        alternate MDB is at block 0 0x00
        primary VHB is at block 2 0x02
        alternate VHB is at block 1952491198 0x74622d5e
        sector size = 512 0x200
        VolumeObject flags = 0x07
        total sectors for volume = 1952591200 0x74622d60
        total sectors for embedded volume = 0 0x00

I absolutely need to be able to boot to use it as an external monitor.

Best Answer

About three years ago, I ran into the exact same problem you're having. The issue is with the hard drive itself--nothing software related. Take it to the nearest/best Apple repair store and have them replace your hard drive. You can then restore all of your information from your backup. You do back up your computer, don't you?

(Note: if you forgot to back up your computer recently or otherwise cannot access your old files, the repair shop will most likely be able to recover most, if not all, of your data. If the HDD is really badly damaged, however, you're best bet is to send it to DriveSavers for a cleanroom disassembly and data recovery. If you choose that option, however, be prepared to spend several hundred dollars.)

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