You might want to look at a Drobo or DroboPro as a possible upgrade. It's not as geeky as doing it yourself with Linux, but it sounds like it's a critial business server so the investment in a little hardware to save you time may be worthwhile. Drobos allow you to swap one drive at a time to grow your available storage, so you can swap a single drive, let the Drobo rebuild, swap the next drive, rebuild, and keep your data live at all times. (http://www.drobo.com/) Main downside is connectivity: USB2 or Firewire 800 for the standard 4 drive Drobo. DroboPro supports 8 drives and adds iSCSI, which is nice if you have a GigE switch. (Linux and Windows have built in iSCSI support, Drobo provides an iSCSI initiator for MacOS) The Drobo presents itself to your computer as a 16 TB drive (for the standard Drobo). You have to use the Drobo Dashboard or go by the lights on the Drobo to see how full it really is. They are nice little units for cheapish mass storage. Data Robotics' support isn't full enterprise level, but for 1 person or SMB I think it's acceptable. A couple friends have pointed out that you have to pay for firmware upgrades after included manufactures warranty runs out. Seems like an acceptable trade-off. Currently running a pair of the 2nd Gen 4 drive units on a MacOSX server for archiving data as they were a cheap stop-gap measure while waiting for budget dollars for an enterprise class archival storage. The Drobos are mirrors of each other so we periodically test drive failure by pulling a drive out. No issues so far. Whatever path you choose, make sure you back it up. RAID (and Drobo's BeyondRAID) is not backup. ;-) -- Andrew S. Zbikowski | http://andy.zibnet.us IT Outhouse Blog Thing | http://www.itouthouse.com