Windows 7 – Install With Multiple Disks

I set out this evening to install Windows 7 Ultimate on one of my “high end” desktops, and like all my desktops it has multiple SATA drives running in AHCI mode (after all, it’s “high end”).

No matter how I setup my drives in the BIOS or with the SATA cables I kept getting the larger (newer) drive as DISK0 in the Windows 7 install and the smaller (older) drive as DISK1.

Finally I started doing some reading on the Internet, and I’m not the only person who’s noticed this behavior.  In fact, some say it’s random.

Based on what I’ve seen and what I’ve read I suspect that Microsoft’s EFI BIOS implementation re-polls [discovery] the drives and ignores what the PC legacy BIOS tells it… and the first drive to respond is DISK0.  In my case the drive I want to be DISK0 is probably predictably slower than the drive I want to be DISK1, so I see consistent results.  However, if the drives are very similar (or identical) you could see either become ready first (a micro-second counts).

This is obviously a bug in Windows 7 (didn’t happen in Vista; but apprently is did happen in Vista SP1 and SP2), and can cause all kinds of problems down the road.

What’s the best way to deal with it?

Open up your case and unplug all but the first drive, do your installation, then power up the drives one-by one (if you have hot-swap capability with SATA you don’t need to power down, if you don’t you will have to power down to plug in each drive in turn).

You can easily change the drive letters in disk manager; and once Windows tattoos the drives they should be fixed in order in disk manager.

If you have a motherboard that uses the Intel chip set you may want to download and install the Intel® Matrix Storage Manager for Windows 7.

If PCs used EFI BIOS (like Macs) this probably wouldn’t be an issue, but since Microsoft uses a soft EFI BIOS to boot, they should have tested this better, and they should have fixed it (there are several people who indicated they reported this behavior during the beta testing).

While Windows 7 might be a nice overhaul of Vista; it’s not without it’s problems, and maybe the whole PC heritage is beginning to be too antiquated to keep updating; perhaps it’s time for a new design.

Originally posted 2009-11-12 01:00:38.