Jose Barreto:It’s very common for a server running Windows Unified Data Storage Server and the Microsoft iSCSI Software Target to include a RAID controller and many hard drives in the box. I got a question on exactly how to configure RAID volumes for this kind of setup. The standard “it depends” engineering answer does apply here. However, allow me to elaborate on that :-).

First of all, it helps to understand a few details about the hardware. The main thing here is the types of RAID supported by the controller (RAID 0, 1, 5 and 10 are common, RAID 6 is sometimes available). It’s also important to know how many physical disks you have there, since this will impact you options (RAID 1 requires 2 disks, RAID 5 requires at least 3 disks).

Second, you need to be more specific about your high availability, capacity and performance requirements. You see, striping all the disks into a single RAID 0 volume with no fault tolerance will give your maximum capacity, but if you lose a single disk, you lose data. You can use RAID 5 to offer fault tolerance without much impact to capacity, but your performance will suffer, especially if a failed disk is replaced and you need to rebuild the parity. RAID 1 (mirror) offers good performance with disk fault tolerance, but you will basically slash your storage capacity in half.