SSD RAID: Do You Want A Cheap Array Or One Larger Drive?

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You're on a budget. You want to know if it'd be better to stripe a couple of smaller SSDs or simply buy one larger performance-oriented drive. Today we're comparing one, two, and four 30 GB Kingston SSDNow V drives to Zalman’s new 128 GB N-series SSD.

SSD RAID Configuration Issues

We had a few technical points to check before we could get started with the tests for this article. Windows does not like it if you switch a SATA controller from AHCI to RAID mode or vice versa. At the very least, you typically have to reinstall the drivers. AHCI is required for an individual drive, and the RAID setup requires a reconfiguration with RAID support turned on.

In order to avoid an inevitable crash when we switched from AHCI mode to RAID, we moved the primary system drive to a HighPoint Rocket 620 PCIe-based controller. This one is SATA 6Gb/s-capable, and it’s a fast and reliable AHCI device.

As a result, we freed all six SATA 3Gb/s ports of the ICH10R controller for either the Zalman drive or the Kingston SSDNow V RAID array, and we were able to switch back and forth from RAID to AHCI. Keep in mind that such a controller change is only possible for AHCI devices, as the system would not be able to boot if you changed the controller on non-AHCI systems.

This is what we did to get the system started:

  1. Duplicate the system drive (backup, just in case)
  2. Attach the system drive to the HighPoint Rocket 620 controller
  3. Attach the Kingston or Zalman drives to the ICH10R (AHCI mode)
  4. Installation of Intel Rapid Storage Drivers
  5. Benchmarking of the individual drives
  6. Switch ICH10R from AHCI to RAID
  7. Setup the RAID configurations (Kingston SSDNow V 30 GB drives)
  8. Enable controller write caching
  9. Benchmarking of the RAID setups

At first, we weren't able to generate decent throughput numbers using the RAID array. Both the CrystalDiskMark and h2benchw metrics reported results of 10 MB/s, which is pathetically low. We should be hitting 200+ MB/s here, and we couldn’t achieve higher results, even after recreating the RAID array. The solution presented itself when Intel’s Rapid Storage Driver GUI crashed. We decided to uninstall and freshly install the storage driver package, and then saw great performance numbers within the expected range. Keep in mind that drivers might be sabotaging your storage performance next time you’re seeing numbers that just don't add up.

Patrick Schmid and Achim Roos