The drive has to have a Dell firmware on it to be compatible. There is no (cost effective) way to take a generic drive and put the Dell firmware on the drive, so your only choice is to buy the drives from Dell or a reseller (e.g. via Ebay).
I've got a MD3000/MD1000 array attached to my Dell PE R805 running Win2008 R2 SP1. I've made sure all firmware and drivers have been updated to the latest version (I'm in the process of setting up a failover cluster with another server). In the process, I'm adding additional drive to expand as well as add a witness disk. The drives I'm trying to add are Seagate ST2000nm0001 (Constellation ES). Everytime I slide one it, the array light goes orange and loses contact with MDSM. If I pull the drive out, the array will right itself and reconnect with MDSM after a minute or so. MDSM suggests that 1) the array is turned off, 2) the network is unplugged, or 3) there are too many TCP/IP connections (?!). Any thoughts?
MDSM loses communication to MD3000 when new disk inserted