Mac Pro with OS X 10.4.7 does not support Hot Swap SATA operation.

To be extremely clear, Apple do not claim or advertise that the Mac Pro to supports hot-swap. They are careful to use the terminology direct-attach installation system. None the less, it is informative to explore the physical and logical limitations of your new system.

Electronically, the Intel®  631xESB/632xESB I/O Control hub supports hot-swap operation. The physical drive mechanisms use the hot-swap style data and power connectors and appear to my untrained eye very similar to the physical configuration used in other hot-swap device bays. (The only visible difference is in the complexity of the drive bay release mechanisms, which does not appear to have an additional electrical element.)

For the record, let it be known that the following hot-swap tests fail in OS X 10.4.7 desktop version:

Test 1

Configure a Mac Pro system with two drives with non-raided configuration (two drives, each drive with a single partition). The first disk is the boot drive, the second disk is a drive for sharing non-essential data. The system is booted with the boot-drive operational, and the second drive physically unconnected.

Insert the second drive. The drive powers up.

Unfortunately, the operating system (Desktop Tiger version 10.4.7), does not recognize the presence of the new disk. That is, it is not present in Finder and it is not present in /Volumes folder.

Not content to say, “it can’t be done”, I load up disk utility. Not only is the second drive not present, there is no way to force a system-wide “scan for new drives” operation.

You must physically reboot the system to detect the drive.

Test 2

Configure a Mac Pro System with two active drives in a non-raid configuration, the first disk is the boot drive, the second disk is a drive for storing non-essential data. The system is booted with both drives operational. The first obvious issue, is that, unlike a USB drive, there is no method offered by Finder to safely eject our secondary (non-essential) drive.

So lets assume that the second drive is removed from the system. The first fault is that finder is not integrated into the Intel southbridge chipset sufficiently to detect that the (forced) removal of the drive. The secondary fault which follows on from the first, is that selecting or opening a file that is not previously stored in cache results in the system becoming unstable. If the file is selected using Finder, Finder becomes unresponsive.

To correct this issue, you must physically reboot.

Summary

I suspect that Apple could improve the 10.4.7 desktop operating system to detect the insertion and removal of SATA drives on the Mac Pro System. I would be very interested to know if the above tests work with a 10.4.7 server operating system.

I hope this is not a ‘marketing’ issue, like with the old iBooks that disabled the dual-screen option to differentiate there low-end, high-end laptops. (ie., Workstation Mac Pro vs Server grade Xserve).

Last Updated: 2009 November 15