From which plex am I booted from on raid

First of all, it is possible. However I think, that you won't get that much of a benefit from it.

I was in nearly exact the same situation, only, that I dealt with a Windows Server 2008 (not the new one with the Windows 7 kernel). But I don't think, that it will be much different.

Windows RAID relies on dynamic harddrives. So basically all you have to do is:

• install the second hard drive
• convert the first and the second drive to dynamic ones in Disk Management (Server manager -> storage ...)
• then you should get the option of creating a mirror for either volume via right click (obviously you want to mirror the boot volume)

It will then modify the boot manager (you'll get another entry for the second hard drive to boot from) and start syncing. While the sync is in progress the complete server (it was a small tower Dell PowerEdge T105) was VERY sluggish. Sync takes sometime (some hours for 80 GB...) .

Then the problems begin:

• you won't notice, when a drive fails... so you have to create some scripts on your own
• even worse, if the first drive fails, you'll be stuck at the boot option selection screen
• I tested the whole setup with in a VM and the results were not very promising:
  • once one drive was disconnected windows would not resync to it anymore
  • the first boot drive was still a dynamic disk but I could not add mirrors anymore either ...

All in all I don't think that Windows software RAID on the boot drive is a good idea. Don't get me wrong, I've been happily using Windows software RAID on data discs for years, but I think it is not robust enough yet for boot drives.

If that is not discouraging enough, I'd advise you to test the whole thing in a virtual machine. You can get the evaluation version of Windows Server from M$' web site or simply use your own install media without entering the product key. VirtualBox will happily run it...

The solution was very subtle, and a horrible design idea by Microsoft.

The two original Western Digital Caviar Black 1 TB drives were listed as 931.51 GB:

But the new disk was 931.39 GB (120 MB to small) - even though the drives are the same size.

In a flash of inspiration i realized that Guid Partition Table might take up more space than a Master Boot Record partition. We converted the drive back to MDR.

The drive then appeared to be 931.51 GB, and the Repair Volume option was no longer greyed out.

So, when Disk Manager tells you nothing about what the problem is - it might because there is no drive large enough to act as a replacement. And The size of the plex member is invalid. might mean that the drive is not large enough to hold the needed volume.

i especially liked the part where Disk Management told us nothing at all.