Mac Pro problem only when 4th HD is installed

[digitaldch]

I've got a strange Mac Pro hard drive issue that I'm wondering if anyone else has experienced.

Originally purchased my Mac Pro with the single 250GB configuration (it was the Seagate). My local CompUSA had a great sale on 250 GB WD Caviars, so I bought 2. I installed them and loaded Boot Camp 1.1 & Windows XP onto Drive 2. I then formatted Drive 3 as an extra Mac volume. A quick check with SiSoftware Sandra Light under Windows showed I was getting fast response times (59-60MB/s) across all 3 drives and all was good...

Things turned strange once I decided to grab another 250GB Caviar to install into the Drive 4 bay to use as a backup volume for Windows. I installed the drive and it was clearly only working in PATA mode. I then tried a couple approaches to see if I could improve things:

1. Tried reinstalling Boot Camp 1.1 drivers...no dice.
2. To see if it might be a problem with the new Windows drive, I pulled the extra Mac drive from Bay 3 and put the new Windows drive in its place. Everything works again...all 3 drives getting 59MB/s.
3. OK, so it looks like Bay 4 is the problem, but just to make sure I pull the Windows drive from Bay 3 and put it into Bay 4 (leaving Bay 3 open). Everything still works great...59-60MB/s.
4. I put the Mac drive back into Bay 3 and I'm back to square one...59MB/s on 3 drives, slow as molasses on the 4th drive.
5. Figuring it must be because Boot Camp is still beta, I pulled one of the drives and just used 3 for a while. Once Boot Camp 1.1.1 came out, I upgraded and tried again...same results. Ditto for Boot Camp 1.1.2.

As long as I only have 3 drives installed, I get fast performance from all the drives...doesn't matter which bays they are in. As soon as I add the 4th drive, performance on one of the drives (usually the one in bay 4) tanks.

Anyone else seen anything like this or have any suggestions?

Thanks!
Dave

 

[StealthRider]

Try it with only your Mac boot drive in Bay 4 and see what happens.

 

[digitaldch]

Mac boot drive in bay 4 (alone) works like a charm...

 

[tyr2]

Did you apply the SMC Firmware update that came out a while ago, if not that could be worth a try.

Also worth checking the drive manufacturers websites for firmware updates for the disks.

 

[digitaldch]

I did apply the SMC Firmware update but still no go.

I'll double check for drive firmware updates, but the fact that the same drive works fine when there are only 3 drives loaded leads me to suspect it is something to do with the SATA controller and/or the added strain when all 4 drives are loaded

 

[jaguarx]

Is this just under windows or OSX as well?

 

[digitaldch]

I haven't been able to confirm the read speeds on the Mac side of the house, but it has acted strange even when running under OS X with all 4 bays loaded.

The extra Mac volume has refused to load. I can see the drive in Disk Utility, but it refused to load to the Desktop. Take out one of the other drives and it loads fine.

All of which makes me suspect a hardware issue, so I was hoping to get some confirmation that others had seen similar behavior, but it doesn't sound like it...

 

[jaguarx]

Sure as hell sounds like a hardware issue to me. Time to call Apple.