Eric's Technical Outlet

Learning the hard way so you don't have to

Microsoft Storage Spaces vs. AMD SB950 RAID

This is a quick comparison of a parity Storage Space vs. RAID-5 on the same system.

I recently built a new desktop system from components. I selected a Samsung 850 EVO for my primary system and application drive. For longer-term storage and more static installations, I’m using 3 WD10EADS (1.0 TB Western Digital) drives. In my previous build, I used these drives in a RAID-0 for faster storage than my primary. The motherboard that these are attached to is an Asus M5a99FX. After assembling it, I noticed that the south bridge on this board (AMD SB950) supported RAID-5, whereas my previous board did not.

I had a great deal of trouble getting this system to work in RAID mode at all. What I wound up doing is moving the EVO to one of the ASMedia connectors on the board. I don’t know what their technological differences are, but their connectors are blue and they’re excluded from RAID mode. That allowed me to install Windows (before you suggest it, no, loading the RAID drivers during Windows installation does NOT allow it to detect the RAID system). In order to configure the RAID array, I had to set the Asus BIOS to use the RAID controller in “Legacy Mode”. You can set it to UEFI, but from there I couldn’t figure out how to configure the thing (maybe with AMD RAIDXpert?).

So, that worked, and did what I needed. After looking through the RAIDXpert tool, I learned that, unlike a real RAID system, you have to manually configure patrol reads and scrub operations. So, I did that. And then, on the day that the scheduled scrub occurred, it completely locked up my computer. For about 24 hours. By “locked up”, I mean that the only thing I could do was move the mouse. No clicks, no keyboard, nothing else at all. Well, I don’t want to not use patrols and scrubs, but I also don’t want my computer locked up for an entire day (and really, why does a patrol read take that long, especially at 100% horsepower?). So, I thought about using Windows Storage Spaces in parity mode. I was on the fence about that. It’s “fake RAID” in much the same sense that the SB950 is, but other than that, I couldn’t think of a real reason not to use it. I figured I would let benchmarks help me decide. So, I ran a benchmark on it while it was still in RAID mode, then I deleted the RAID, set the controller mode back to AHCI, and configured a parity Storage Space on those drives and ran the same benchmark.

Here are the results:

AMD SB950 RAID-5 Benchmark

AMD SB950 RAID-5 Benchmark

Parity Storage Spaces Benchmark

Parity Storage Spaces Benchmark

Parity Storage Spaces had somewhat faster write performance but dramatically faster read performance. That helped me make my decision fairly easily.

Benchmarks were performed with ATTO’s disk benchmarking tool on Windows 10.


2 responses to “Microsoft Storage Spaces vs. AMD SB950 RAID

  1. Kam December 22, 2015 at 9:25 pm

    What is the “transfer size” drop down and what effect does that have on the benchmarking? They’re different between your two bench runs


    • Eric Siron December 23, 2015 at 10:10 am

      The transfer size is how many kilobytes are used per I/O operation. I did not know in advance that the Storage Spaces volume would not be able to use anything smaller than a 4KB chunk. Just ignore .5, 1.0, and 2.0 on the Raid-5 result charts because there is nothing to compare them to. The rest of the numbers have an entry on both charts.


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