September 23rd, 2006 • 5:37 pm
I’ve now switched back to the G5 Quad as my main machine and did a clean install of Mac OS X 10.4.6, just in case the 10.4.7 update played a part in the problem. I reinstalled all my software and used SuperDuper! to update my documents partition to match the one on the G4 MDD. I also didn’t reconnect my second display (the 23″ one) right away. And then I started using the machine again.
Sure enough, I got a freeze within 24 hours. The freeze occurred while working in GarageBand. Not only did the whole screen freeze (including the mouse pointer), but the audio playback of GarageBand itself also froze and started repeating a loop of sound endlessly.
Out of curiosity, I went to my G4 MDD and tried logging in remotely via
ssh, since I had activated remote login on the G5.
Much to my surprise, the G5 was very responsive and allowed me to log in without any difficulty. I was then able to run the
top command in Terminal, and the list of processes looked perfectly normal, with
top itself at the top with more or less 10% of CPU, as expected, and the other processes still running, without saturating the processors or anything.
The fans on the G5 Quad soon kicked in, indicating a loss of control of the temperature monitoring process (and the red LED came on in the front), but based on what
top was telling me, behind that frozen façade the machine was still running just fine.
I don’t know enough about using Terminal to monitor a machine remotely to do much beyond this, however. I don’t know if there’s an easy way to see if one particular process is frozen.
I tried to shut down the machine remotely using
shutdown -h now, and the shutting down sequence did begin on the G5, based on the feedback I got through Terminal… but it never did complete, and ultimately I had to do a hard reset of the G5 just the same.
I find this quite intriguing. It certainly seems to indicate that the temperature controls are involved, but that the core of the machine (the CPU, the RAM, the hard drives) are not directly affected by these freezes.
Still, that doesn’t tell me what to do to avoid the freezes or indeed to trigger them reliably.
I got on the phone again with Apple, and inquired about whether there was anything that I could try and do remotely via
ssh when a freeze happens, but the tech support representative didn’t have any suggestions. He didn’t seem to think that there was anything that could be done via “software” (his words) and that my clean install of Mac OS X had pretty much ruled out a software issue anyway.
So now I really do have to take the machine to the repair shop and try and see if they have any other, more powerful diagnostic tools that could help them identify the source of the freezes. I will set up an appointment on Monday and will just have to drive there (a six-hour round trip), I am afraid.