"RAID Migration? What the heck are you Tom’s Hardware people doing now?" Once again, we are doing what we believe we do best: testing and benchmarking scenarios that occur in every day life, and providing information that may come in very handy to enthusiast users and administrators. RAID Migration has nothing to do with RAID level migration, where you change an existing RAID configuration into a different one. RAID migration rather refers to porting an existing RAID array from one mass storage controller to another. This is an important issue whenever you change your hardware; it happens most frequently when people decide to upgrade their system’s platform (motherboard, CPU, RAM and so forth). Since the actual implementation of RAID arrays isn’t defined anywhere - RAID levels define only what to do, but not how to do it - the so-called "RAID signatures" of various controllers can vary, and moving an array from one to another may render your fully featured RAID array useless.
When we were playing with different Windows installations on various RAID controllers to find a good setup for our RAID Charts, we often had issues with re-using the installed RAID arrays on different controllers. If you’re running your system hard drives in a RAID configuration, you might be interested to know whether or not it is possible to migrate your storage array to your new dream platform. Think of a three year old motherboard with a storage controller that you used to create a RAID array for your Windows installation. Will you be able to migrate the existing array to a newer on-board RAID controller? Are there workarounds if it doesn’t work? And perhaps most importantly, would you be able to rollback the whole process without losing your RAID array data if there is a problem?
For this test, we searched our hardware dungeons for suitable platforms. We decided to go back in time to the year 2003, when RAID controllers were first integrated into chipset Southbridge components. Intel’s ICH5R, which was an option for the 865 and 875 chipsets, first offered two Serial ATA/150 ports with support for RAID 0 and RAID 1. The ICH6R from 2004 (915, 925 chipsets) increased the SATA port count to four, and ICH7R first introduced support for RAID 5 and Intel’s Matrix RAID feature, which allows users to install more than one RAID array across one set of hard drives. In addition to Intel chipset boards, we picked one nForce3 motherboard, as well as a solution based on VIA’s K8T800 Pro (VT8237 Southbridge). And we also found an old Promise FastTrak 20378 controller, which can be found integrated on various enthusiast motherboards and stand-alone RAID cards Compare Prices on RAID Cards.
We then selected three storage controllers/Southbridges that represent the majority of systems used today: AMD/ATI’s SB600, which is part of the AMD690 chipset and the AMD/ATI Crossfire Xpress 3200; the Intel ICH9R that is part of the P35 and the upcoming X38 chipsets for Intel’s Core 2 Duo CPUs; and Nvidia’s nForce 590, which is still the most popular chipset for Socket AM2 solutions and the Athlon 64 X2. All of these support AHCI mode and various RAID configurations, but all we wanted them to do is accept the existing RAID arrays from our source platforms.