|Source Platform||Target Controller||Successful Migration Possible?||Port Change Possible?||Plug & Play||Migrate with Windows Repair Installation||Rollback if Failed|
|Nvidia nForce3||Nvidia nForce 590||yes||yes||-||yes||-|
|Promise FastTrak 378||Nvidia nForce 590||no||-||-||-||yes|
|VIA VT8237||Nvidia nForce 590||no||yes||-||-||yes|
|Intel ICH6R||Nvidia nForce 590||no||-||-||-||yes|
Our migration efforts to the nForce 590 weren’t very successful unless we used an nForce 3 source system. Using the Promise controller, an Intel or a VIA source system, the existing RAID arrays weren’t even recognized; the system reported only empty hard drives. This is rather dangerous if you’re working with more drives, as you could confuse the RAID drives with other drives that might indeed be empty, and destroy your RAID array accidentally. The VIA controller’s RAID array was detected as a broken RAID 5 array by the nForce 590 MCP.
Migrating RAID arrays from one controller to another one is possible under only limited circumstances, due to the different implementations of RAID and hence different RAID signatures from controllers. We found that it is possible to migrate RAID arrays within controllers from the same manufacturer; for example, we were able to migrate any RAID array built on an Intel ICH5, ICH6, ICH7 or ICH8 controller to the ICH9. Going from the ICH8 to ICH9 didn’t require any effort at all, as the storage units seem to operate identically. Going from nForce3 to nForce 590 was also smooth, as was the transition from the Promise controller to the ATI/AMD 690 chipset and the SB600 Southbridge, as they are based on the same controller logic Compare Prices on RAID Controllers.
Even where successful, all migration procedures required a Windows XP repair installation, which is triggered by booting from the installation CD and selecting "Repair" instead of "Fresh install" at the time you choose the target partition. Luckily, it is always possible to stop the migration efforts and move a RAID array back to its initial controller without losing data.
So far, so good. But the tests for this article extended over more than a week, which shouldn’t be the case considering that even on-board RAID controllers have become very mighty. Multiple RAID modes and even multiple RAID installations on the same set of hard disks are easy to configure for up to six drives. Nvidia’s software will tell you if a drive fails, and it even tells you right under Windows which one to replace. But none of the controllers, whether the AMD SB600, Intel’s ICH9 or Nvidia’s nForce 5/6 MCP, can reliably discover an existing RAID array, let alone import one.
This clearly is an area that requires improvement, although we realize that it’s not easy: the actual implementation of RAID arrays is different across various manufacturers, as there is no specification. According to information we received from companies such as CBL Data Recovery and Kroll Ontrack, the RAID controller manufacturers aren’t cooperative when it comes to their RAID implementations.