Mac Crash
It’s not often my Dual 1Ghz G4 PowerMac crashes, but it happened to me last week. I’m not totally clear on what caused it, but it had something to do with disconnecting a USB device. The cascading grey screen of a kernel panic appeared along with little white text telling me I needed to reboot. So, I did and kept getting the same thing.
From my experience, the most likely cause of such a “kernel panic loop” is hard disk corruption that occurs during the initial crash. To confirm it was a problem with my hard disk and not some other part of the machine, I hooked up a Firewire hard drive containing a backup of the PowerMac’s boot disk. For some odd reason I haven’t determined, the PowerMac would not see the Firewire hard drive during the boot up; I got the machine to boot by selecting a Jaguar partition on the boot hard disk and then into Panther on the Firewire hard drive. Panther came up without a problem, albeit an older version than the one the PowerMac had been running.
Since all my applications were also cloned onto the Firewire drive, I opened a version of TechTool Pro from the Applications/Utilities folder and had it run Volume checks on the original Panther boot drive. Sure enough, it detected an “allocation overlap” error in the boot sector. I told it to repair it, and it got to work.
Using Tech Tool to repair a boot sector on a hard disk is always slow going. It literally took all day for the software to make a repair, and three tries to ensure it did it all. The repair process hung twice when the monitor (and the monitor only) was turned off by OS X’s Energy Saver. I disabled the energy saver altogether and checked on the Mac continuously to make sure the disk repair was working. A watched computer never crashes. Well…almost.
If memory serves, this was the second crash of the same type I’d suffered recently. Both of them had occurred since I reconfigured the PowerMac to run only Western Digital hard disks. One more crash like that and I’m going to swap them out with equivalent Maxtors. That’s the only way I can establish if the WD’S are in some way contributing to the problem.
From my experience, the most likely cause of such a “kernel panic loop” is hard disk corruption that occurs during the initial crash. To confirm it was a problem with my hard disk and not some other part of the machine, I hooked up a Firewire hard drive containing a backup of the PowerMac’s boot disk. For some odd reason I haven’t determined, the PowerMac would not see the Firewire hard drive during the boot up; I got the machine to boot by selecting a Jaguar partition on the boot hard disk and then into Panther on the Firewire hard drive. Panther came up without a problem, albeit an older version than the one the PowerMac had been running.
Since all my applications were also cloned onto the Firewire drive, I opened a version of TechTool Pro from the Applications/Utilities folder and had it run Volume checks on the original Panther boot drive. Sure enough, it detected an “allocation overlap” error in the boot sector. I told it to repair it, and it got to work.
Using Tech Tool to repair a boot sector on a hard disk is always slow going. It literally took all day for the software to make a repair, and three tries to ensure it did it all. The repair process hung twice when the monitor (and the monitor only) was turned off by OS X’s Energy Saver. I disabled the energy saver altogether and checked on the Mac continuously to make sure the disk repair was working. A watched computer never crashes. Well…almost.
If memory serves, this was the second crash of the same type I’d suffered recently. Both of them had occurred since I reconfigured the PowerMac to run only Western Digital hard disks. One more crash like that and I’m going to swap them out with equivalent Maxtors. That’s the only way I can establish if the WD’S are in some way contributing to the problem.
posted by Andy Foster at
2:53 PM
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