I'd like to think I do, at least I've been working with RAID devices at a professional level for several years now. However at home, I purchased a consumer-grade device for use with my Mac Mini media library. OWC Mercury Pro Qx2. I have the thing setup in a RAID-5 array, using a 3+1 configuration (three drives in the array plus a hot spare). More or less, the safest config you can do on this device and still get a reasonable amount of storage. Cut to yesterday morning -- I wake up to the device beeping, to find that one of the array drives failed, as well as my hot-spare. I tried reseating each, one at a time, but...they're bad. My data is still good, but I've now lost the max amount of drives I can lose without replacing a drive immediately. Replacement drives are in the mail and I've backed up my data to another drive just in case. My question stems from reading the device manual. It says that when replacing a drive, you need to replace it with the EXACT same make and model, preferably the same firmware revision, etc. I've never known this to be the case with RAID...it's always been my understanding that as long as you replace the drive with one of equal or greater capacity, it will work, and if need be the array will "dumb" the drive down so it only uses the same capacity as all the other drives. Anybody in here have experience doing this? I'd kind of like to order some spares and NOT get the same make/model that I used before, being that two of them up and died on me at the same time.