Please ask the makers of said monster raid. Here's why. They would have the experience of such expansions and can tell you if PM will do the deed.
Any advice from me is not from experience on your setup, but then again with that much data I bet you have a disaster recovery plan that you could just start over with the size drive you wanted and execute 'the plan'.
Bob
I have an 8 port raid controller (Rocketraid 2220) with 6 400GB drives. Four of them were in a level 5 RAID. I added a fifth drive to the RAID. When the online expansion was completed the Win 2000 Server drive manager showed a 1.6TB drive with a 1.2TB NTFS partition and 400GB of unpartitioned space. Can I use Partition Magic or something like it to expand the partition out to the total size of the RAID? I eventually will expand the Raid to 8 400GB Drives. Would it cause any additional problems if I added the rest of the drives now and then expanded the partition?
Terry

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