Ask Max: Testing a Hard Drive with Bad Sectors
About five months ago I installed a second hard drive in my 1.8 GHz PowerPC G5 Mac, running 10.4.4. A Western Digital 250GB SATA, I formatted it into two drives, and their icons appeared on my desktop. I used them for periodic backups of my main hard drive, among other things.
Then several weeks ago their icons disappeared, I think with the upgrading of my software from 10.4.4 to 10.4.5, but I'm not certain that was the event that eliminated them.
In Disk Utility the drive appears, but I can't mount it unless I partition it again. After partitioning I can copy files onto each partition, and that seems OK until I restart my computer, and then they are gone, requiring me to partition again. Obviously not a solution.
I contacted Western Digital since the drive is still under warranty, and they said that if it shows up in Disk Utility it is a good drive. If it didn't show up, they said, change the cable and if it still doesn't show it is bad and return it. But it seems to be a good drive since it does show up and can be mounted after partitioning.
I thought of reloading my Tiger disk and upgrading again to 10.4.4 and stopping there, but I haven't done so yet.
The first thing that comes to mind is that the hard drive has bad sectors on the inner rings that store the partition table. Every hard drive has some bad sectors, and because of that all computers are good at avoiding those bad sectors. Most times, mapping out bad drive sectors works, except when those sectors are in a critical place. I believe that's what is happening to your drive. To test the problem you should eliminate the possibility of your G5 being the cause of the problem. The test is simple. Swap the position of your two hard drives by moving the second hard drive to the top and the boot drive to the bottom. The nice thing about Serial ATA (SATA) is that each hard drive has its own data cable, independent from the other drives. If the problem follows the drive and not the drive bay, you can be confident it is a hard drive problem. One last thing to check is if you are formatting the drive properly. It should be formatted as a "Mac OS Extended (Journaled)."