Windows vs Intel Raid Performance Smackdown

Update: Turns out I was pretty wrong about Storage Spaces and have been totally schooled and corrected about them here, on Reddit and at Redmond.  I’ll be revising this post heavily, adding some iometer numbers.  Stay tuned!

In this post, I’ll share my results comparing hardware to software RAID on modern Windows 10, then to take things up a notch, I’ll see how a Storage Spaces volume with Parity (maybe Microsoft is charged money for using the word ‘Raid’, because they avoid that word like the plague!) compares to the hardware solution (Spoilers: it ain’t pretty) in pretty much every configuration I could think of.

I’ve had a lot of issues in the FoxDeploy lab recently. Two months ago, I had a number of SSDs in a Storage pool on Server 2012 R2, then decided I should go to the desktop experience, and moved to Windows 10.  Let’s call this rebuild #1.

Since then, I’ve had an SSD fail in a Windows Mirror, resulting in a total loss of VMs, as I didn’t have backup working.  Rebuild #2

Next, I decided to take three drives, two physical SSDs and a chunk of unpartioned space from a six year old spinner, and put them in a Raid-5.

As it turns out, this kills the drive.  Goodbye, Big Betty, I will miss you. Rebuild #3.

At this point, I had it with these janky solutions.  I’ve recently come into possession of some new SSD drives, and this time, I’m going to do it right, damn it! I wanted to finally have some resiliency in case one of my drives died.  But along the way, I needed to know how it would perform.

Findings – Raid 0 Testing

For starters, here’s our benchmark.  It’s a single OCZ 120 GB SSD disk, connected via 3GBPS sata.

Single disk, sata 3
Single Disk Performance

Not bad, very respectable. Now, let’s see what happens when I use Windows to take two of these and stripe them. This is also called Raid 0, as in ‘you have zero parity and are totally hosed if one of these drives dies’.

Expectations: You gain the full capacity of both drives and speed to spare, as data is randomly written across drives.  Speed should be roughly double that of a single drive.  However, if one dies, you are up a creek, because you will not be able to recover your data. You’ll tend to get ~double the read and write performance when striping.

two disks, SATA 3, windows raid 0
WIndows Raid 0

If we compare the two, we see roughly double the performance as well.  Windows raid is achieving parity via the OS. Since data striping (putting chunks of data on the disk) is handled by the operating system, there is a potential for disk performance to suffer when the rest of the OS is under heavy load.  Microsoft has had years to work out the errors and speed things up though, so don’t let this stop you if your motherboard doesn’t support Raid.

Now, Let’s see how Windows Raid-0 stacks up to actual hardware raid.

TWO DISKS, SATA 3, Hardware RAID 0
Hardware Raid 0

To put those side-by-side, here’s the difference you can expect when comparing hardware Raid-0 to Software Raid-0.

Raid0 testing
Intel Performance Increase over Microsoft

Winner – Intel
There is quite a performance edge to gain by using a hardware controller, even nowadays. I was very surprised to see such a disparity here.  In every regard there were noticeable speed gains, at least on paper.

Findings – Raid 1 testing

Now, these big numbers were very fun, but as I’m doing this to test my performance while operating safely with parity, I needed to see what would happen when actually using mirroring.

Expectations – With Raid 1, you should receive roughly double read speed, while writes will suffer, because of the need to create and distribute parity sets across disks. You lose the whole capacity of one drive, but have a full backup of your active volume in case it dies. Nothing is safer than Raid 1!
First, I tested in Windows for Raid 1, also known as a ‘Mirrored Set’.

Windows Raid 1

Wow, the reads are still good, but boy does the writes take a huge faceplant. Writes were roughly half of the write speed for a single drive, which was surprisingly bad, in my opinion.  Functionally, this makes sense, as the OS has to track syncing writes to two different disks.  Who knew that it would levy such a heavy penalty though.

Now, to compare this to using dedicated Raid hardware.

TWO DISKS, SATA 3, hardware RAID 1
Intel Raid 1

While the Intel raid controller blows the Software Raid out of the water on sequential reads, surprisingly the Windows software Raid was better in nearly every other respect. It seems that no matter if you use a hardware or a software Raid controller, you should expect to lose performance when you’re duplicating every write, which makes sense.

We can compare this to our single disk performance though, and see something else happening.

Side by side, intel % change vs software raid 1
Raid1 testing
Intel % increase over Microsoft Software Raid

Winner – Windows
If you need super fast sequential reads, like you’re working with a single big file that happens to be on one contiguous area of disk, if you could control that, then you’d want the Intel Controller. If not, Windows looks to be good enough, and takes the lead in most categories.

Findings – Raid 5 testing

Raid 5 was the defacto standard for parity across volumes smaller than a TB. Now, it’s been replaced with other Raid and parity options, but it’s still probably the most prevalent way of safely allowing for disk failures without a tremendous speed loss. With Raid-5, you lose the space of one drive.  With that being said, you can get some beefy performance, and have parity!

Raid 5 in Windows 10, some notes before we begin

In this round, we’ll be leaving the Disk Management wizard for Windows and instead go into the control panel to create a Storage Space!  Previously, there was no way for end user running home or PRO Windows to do make a parity volume, which reserved that feature for Windows Server users only.  Storage Spaces is Microsoft’s new, much easier to use approach to Disk Management with loads of options.

You can configure this any way you want to! Just spend a LOT of time reading documentation.
You can configure this any way you want to! Just spend a LOT of time reading documentation.

While Microsoft doesn’t call it ‘Raid 5’, it’s possible using Storage Spaces to create a Parity Pool, which will effectively achieve the same results.

Raid-5 by any other name. Double Parity would be Raid-10!
Raid-5 by any other name. Double Parity would be Raid-10!

It should be noted that I had to tune this array to get these results.  First off, a default Storage Spaces drive will be created with a Write-back Cache of 1 GB.  It should also be said that there IS a distinct performance penalty at play here.  In order to play things safe, there is some mandatory disk journaling involved here, meaning that your writes aren’t going to be cached very much.  Instead, the storage subsystem will wait for confirmation of all writes, and it does so VERY conservatively.

It’s not uncommon to see R/WR delays into the tens of thousands of milliseconds while writes are performed.  You can somewhat minimize this behavior by running these two PowerShell cmdlets.  The first GREATLY boosts the write cache amount, which I’ve seen to boost performance, while the second cmdlet specifies that there is Power protection (like a UPS).  To quote the help documentation ‘If you specify a value of $True for this parameter, the storage pool does not perform flush operations, and the pool removes write-through attributes from commands.’  It also helps.

Get-StoragePool | select -First 1 | set-storagepool -WriteCacheSizeDefault 8GB
Get-StoragePool -FriendlyName “Storage Pool” | Set-StoragePool -IsPowerProtected $true

Now, after that length pre-amble, let’s hop to it.

Hardware Raid 5

As expected from hardware Raid 5, we receive roughly 100% read speed from all drives, for some truly mammoth read speeds.  Writes hang out around 2/3rd’s of the total write speed for all drives, making this the power-user’s option.  It should be noted that I had to specify a custom disk policy for this Raid 5 volume to enable write caching and disable flush operations.  This is definitely a power-mode configuration, but depends on battery backup to ensure there is no data loss.

Be warned, you will lose data if you have a power outtage. Only check these if you've got reliable UPS in place.
Be warned, you will lose data if you have a power outtage. Only check these if you’ve got reliable UPS in place.

If you’re using Raid 5, you’re probably data loss averse, so only specify these settings if you’ve actually got a battery backup.

Now, onto the final option, Storage Spaces with Parity.  This is super secure for your data, however…writes…well…

THREE DISKS, SATA 3, Storage spaces parity volume (raid 5)
Storage Spaces Journaling aggressively protects data, but at a cost
Storage Spaces Journaling aggressively protects data, but at a cost

I reached out to some peers for help, to see if I was mistuning this array, because, frankly, damn.  

According to Aidan Finn, Microsoft MVP of Datacenter and Hyper-V, I’m doing it wrong.  This is not meant for performance, nor is it a good idea for storing VHD files.  You should be using parity volumes as a replacement for a super expensive NetApp or LeftHand SAN Solution, with wonderful configurability for hundreds of potential configuration.  You use this to save money for your archival storage, but shouldn’t expect to get equal performance.

Still, the numbers are pretty shocking.  Here’s Storage Spaces Parity volume compared to a single drive, and to a Raid 5 Volume.

StorageSpace v Everything Else
Great for Reads versus a single drive, but writes suffer incredibly.

Winner – Intel

Now, Storage Spaces can do things you cannot do using a simple Intel Raid Controller.  For instance, you could easily take four full JBOD (Just a bunch of disk) arrays, filled with 8 TB drives and also slap in a stack of PCI-e or SSD storage to create a wonderfully resilient storage system with excellent performance.

But it’s not the answer to every problem.  In this case, the Intel Raid Controller was the clear winner, absolutely smoking the Storage Spaces Controller.  This graph says it all

12,000% improvement in writes is mindblowing
12,000% improvement in writes is mindblowing

In Conclusion

If you want maximum performance for a small number of disks, need some basic parity support, and don’t have more than 13TB in a volume, and you have a hardware Raid Controller, then you should definitely use hardware Raid 5 over storage spaces.

You need maximum speed and will backup your data – Use Raid 0 and backup data

You need maximum speed and some resilience to disk failure – Use Raid 1 or Raid 5

You need to archive monstrous amounts of data across insane configurations of disk arrays – Use Storage Spaces.

Finally, some random charts.

raid 5
Intel RAID-5 performance over Single Disk

raid 1 vs single drive

Did I do it wrong?  Am I missing something?  Correct the author by e-mailing me at, or commenting here.


11 thoughts on “Windows vs Intel Raid Performance Smackdown

  1. matthewf01 October 30, 2015 / 9:16 am

    I’ve been using Storage Spaces since Windows 8 (and survived an ugly update to Windows 10 thanks to a previous post of yours [those dirty 2012 binaries for dedupe got me…]). My main use case for SS is having somewhere that’s parity-protected to park all of the multimedia for my Plex library (currently ~8TB).
    I’m using 4x 3TB Western Digital Red 3.5″ disks to back my capacity pool.
    Speed isn’t critically important for this purpose, but as high bitrate 4K content will one day begin to fill my library, I imagine one day I’ll hit a wall. But for now, 1-3 simultaneous streams of data coming off those disks is well-handled, especially since it’s a mostly-reads environment. Writes happen in the background as new multimedia gets loaded in automatically, so I tend to not notice/care.
    However, what’s nice about SS is that the protection level may be applied PER VIRTUAL VOLUME, rather than for the entire pool/array. This is great because, say I want to create a VM or two for an experiment — I don’t necessarily care about their survivability in the event of disk loss, and I don’t want their performance to suffer under parity calculation. I can create a new virtual volume, call it “Non-Resilient Storage”, and create it as the ‘simple’ volume type, with no protection. Data gets striped across the array, so I get a nice little performance boost.
    I know it’s not the perf levels you’ll get out of hardware RAID, but SS does have a big advantage over your typical consumer-grade built-into-the-motherboard harwdare RAID controller —- THE ARRAY IS PORTABLE. If my motherboard dies on me, and I can’t get the same exact board, and the new one has a different RAID controller, there’s a good chance my array might not work under the new controller, right? That’s a pretty ugly place to be in.
    I had also done testing with FlexRAID, prior to using SS, and it did not pass my resiliency tests (simulating different drive failure scenarios).
    Cool post, thanks for running the numbers!


    • FoxDeploy October 30, 2015 / 9:20 am

      The portability is a huge plus that I wasn’t considering. Thanks for educating me on it! So, what would happen if my raid controller died? I couldn’t just plug the drives into another of the same controller?


      • matthewf01 October 30, 2015 / 10:19 am

        Yes, absolutely if your new/destination RAID controller model is the same as the old one, the array should come up fine. But with all the vendors and even models being integrated into motherboards, it’s not always easy. For this reason, a standalone RAID controller card might be a safe bet, as you can either purchase 2, or more reliably replace it with an identical model in the case of failure.
        Reason being that the metadata/disk layout can vary between vendors and ends up being proprietary in many cases. Enterprise-grade hardware may not work this way, if they’ve standardized on layout.


  2. Taylor Riggan October 30, 2015 / 9:30 am

    Good article! Would love to see what the configuration looked like for the Intel RAID controller (whether you had Write Back Caching enabled, etc.). Also, in one of the images, you mention there being Dual Parity options for Storage Spaces? But that option doesn’t appear in the drop-down. Also, you captioned the image as Dual Parity equals RAID-10. Typically, Dual Parity equals RAID-6. RAID-10 is just mirroring a RAID-0 set to another RAID-0 set. (RAID-0… biggest oxymoron ever, btw. ;))


    • FoxDeploy October 30, 2015 / 9:47 am

      Turns out I was wrong, in that Dual Parity actually means that you can have two disks fail and still survive.

      This new option will allow you to have a storage space that can survive the loss of any two disks.

      A dual parity layout requires at least seven disks. If less than seven disks are present in the pool, the dual parity option will not be visible.

      Thanks for the feedback, Taylor!


      • matthewf01 October 30, 2015 / 10:16 am

        I think the DP option in Storage Spaces is a 2012-only feature?


    • Chance Carroll November 4, 2015 / 10:37 am

      As Taylor Riggan correctly pointed out, in Storage Spaces a Dual Parity drive is comparable to RAID-6, in fact the the Storage Spaces docs explicitly say this is low performance storage to be used for archival purposes only.

      I’m not sure if Taylor just misspoke (misstyped?), but to avoid confusion for readers who may not know, RAID-10 is actually a collection of RAID-1 arrays, with a RAID-0 on top (I believe it was originally know as RAID-(1+0) but I may be mistaken). The RAID-0 is on top so the stripe can span as many disks/arrays/volumes as possible – this is what gives it the performance that makes it so popular in enterprise environments. The magic of RAID-10 is that adding more disk *makes the entire array faster* ! This is also why you will see installations that use many smaller drives instead of a fewer number of large ones – same amount of space but vastly more performant.

      If anyone is interested, an excellent reference on the various RAID levels can be found here:

      The Storage Spaces equivalent of RAID-10 would be a 2 Way Mirror, and if your RAID controller has a cache the equivalent would require enabling Tiered Storage Spaces (and the CSV block cache if you have it as a Cluster Shared Volume) but it will still not be quite as fast as an onboard ram cache.

      I don’t really think Storage Spaces has much to offer think for small, single server storage. I think it does, however, come into it’s own when you need shared cluster storage. A Shared JBOD chassis with 22 spinning disk and 4 SSDs can give fantastic performance, and cost much less than the equivalent SAN.

      All that being said, I also can’t help but wonder if the new 3 Way Mirror has drastically faster reads than the 2 way? I need to see if I can find the hardware to check…


      • FoxDeploy November 4, 2015 / 10:43 am

        Wow, thanks from the awesome post! I’ve learned a lot from the comments here, and am in the process of heavily revising this post, so I’ll be sure to integrate your info onto it if you don’t mind!


  3. Bob March 12, 2016 / 11:59 pm

    Thanks for the informative article. Is there any chance you’d also be able to look into tiered storage spaces (apparently it’s possible via powershell in the current version of windows 10). I don’t think anyone has done a decent experiment and writeup to show if that can mitigate the terrible performance of parity spaces.


  4. Tim Gray June 21, 2016 / 5:45 pm

    What a well researched article – thanks. I’m not any sort of developer, but have always believed in RAID 0 since losing a stash of irreplaceable digital photos a few years back. I was propelled into “Storage Space” after finding that my X79 Marvell RAID controller would only handle two disks. The HUGE write speed difference between the SS and the Hardware RAID has tempted me towards a hardware RAID controller – I think I will buy two now, just in case. Thanks again.


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