Mac Pro Special Report: Freezes during heavy disk activity

CNET staff

Sept. 2, 2009 12:02 a.m. PT

3 min read

We've received some reports of Mac Pros freezing while there is heavy disk activity -- primarily with internal drivers.

MacFixIt reader Helmut writes:

"The freezes occur during writes from a DVD, and other hard drives, to main hard drive. I first noticed the problem when I was installing Final Cut Studio onto the drive - as each DVD was installing, I was surfing the web, and downloading some apps, and kept noticing a spinning beach ball for 10-15 seconds at a time. The installation would go on for a minute or so, then the beachball for 10-15 secs, then the installation would continue for a minute or so, and so on. I had not remembered a simple installation being so taxing on my old Quad G5, and so this behavior seemed odd.

"Later, I installed 3 additional, brand new Maxtor hard drives in the system. 2 300 GBs, which I striped together into a RAID 0, and a 500 GB as well. And whenever I try to copy any appreciable number of files from the main drive to any of these new drives, or from the new drives to the main drive, the system will completely freeze for 10-15 seconds at a time, every 45-60 seconds, during the copy. During this freeze, the copying itself will stop, all apps will stop, no keyboard or mouse input is accepted, iTunes will stop playing, Expose doesn't work, etc. etc. etc., and then, 10-15 secs later, the machine will come back to life, and the copy resumes and all other functions resume....until the next freeze 45-60 secs later.

"But no freezes occur when other hard drives write to each other. This problem does not occur when I try to copy an appreciable amount of data between any of the Maxtor drives. The copies go fast and smooth, and I can do plenty of work in the background."

"Clearly, the problems all occur when the main Western Digital Caviar SE drive is having large amounts of data written to it, either from the DVD drive (Final Cut Studio install), OR other internal hard drives. I don't know if it's the Western Digital hard drive itself that's the problem, or some weird incompatibility between different drives in Apple's SATA system, or what."

Another reader writes:

"I have a Mac Pro (3Ghz, 5 GB RAM from OWC) which came with a stock 250 GB Western Digital Caviar SE hard drive. The system will freeze for 10-15 seconds at a time (everything stops, no input is accepted) when large amounts of data are being written to that drive, but not any other drives I've installed."

Index: