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Results: 128 KB Sequential Performance Scaling In RAID 0

Almost 20 TB (Or $50,000) Of SSD DC S3700 Drives, Benchmarked
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128 KB Sequential Read Performance Scaling in RAID 0

Testing with 128 KB sequential reads, we get almost 2 GB/s from the four-drive array and more than 4.2 GB/s using 24 of the SSD DC S3700s. If we were getting an even 500 MB/s per drive, as Intel specifies, the 24x array would yield around 12 GB/s. Each of our Intel controller cards uses eight third-gen PCI Express lanes, so each one should be able to push more than 4,000 MB/s. 

Still, we're seeing a massive amount of throughput. It's almost like reading an entire single-layer DVD every second. And we can do that speed from the first LBA to the last because we're not relying on any caching. This is all-flash performance.

128 KB Sequential Write Performance Scaling in RAID 0

We get even better performance with writes. The 24x array encroaches on the 5 GB/s mark, falling just short at 4.8 GB/s. The 16x and 8x configurations group together around 3 GB/s, while the four-drive array backpedals just a few percent compared to its read numbers.

When Keepin' it Real Goes Wrong

Make no mistake; these are breathtakingly awesome numbers. But it's hard to shake the feeling that something is robbing us of achieving epic, face-melting benchmark results.

So, what gives, then?

Could it be the strip size we chose for these RAID 0 arrays? No. After extensive testing, we settled on 64 KB chunks. Each 128 KB transfer is serviced by two drives, since 128 KB divided by two equals 64 KB, our chunk size. With enough parallel requests, everything should be good to go.

As we saw on the last page, we still get great scaling with 4 KB random transfers. So, it's probable that we're encountering a throughput issue. Since each drive is capable of large sequential transfers in excess of 400 MB/s, the issue is most pronounced on this page. The SSD DC S3700s can't put out more than 300 MB/s in our 4 KB random testing, and we expect to lose much of that anyway. So it makes sense that we'd run into bandwidth-sapping limitations here, and not there.

After investigating the RMS25KB/JB IR modules, we discovered that they were running in full PCI Express 3.0 mode and fully capable of pushing data back and forth from our SSD DC S3700s with minimal performance impact. As it happens, the culprit is the one thing we really need: our 24-bay SAS/SATA backplane.

Sad but true. Twenty-four total bays are enabled by a trio of eight-drive bays grafted to our server's exterior. Each possesses two SAS 8087 ports (one for every four drives), and they're just not able to get data through unmolested. Whether any backplane would work in this situation is uncertain, and bypassing ours simply wasn't an option for today's experiment.

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  • 0 Hide
    ASHISH65 , April 14, 2013 9:49 PM
    very good review and also helpfull!
  • 0 Hide
    mayankleoboy1 , April 14, 2013 9:52 PM
    IIRC, Intel has enabled TRIM for RAID 0 setups. Doesnt that work here too?
  • 3 Hide
    Novulux , April 14, 2013 10:13 PM
    You have graphs labeled as MB/s when it should be IOPS?
  • -1 Hide
    DarkSable , April 14, 2013 10:34 PM
    Idbuaha.

    I want.
  • 3 Hide
    techcurious , April 14, 2013 11:10 PM
    I like the 3D graphs..
  • 0 Hide
    cangelini , April 14, 2013 11:26 PM
    NovuluxYou have graphs labeled as MB/s when it should be IOPS?

    Fixing now!
  • -1 Hide
    sodaant , April 14, 2013 11:29 PM
    Those graphs should be labeled IOPS, there's no way you are getting a terabyte per second of throughput.
  • 0 Hide
    cryan , April 15, 2013 12:11 AM
    mayankleoboy1IIRC, Intel has enabled TRIM for RAID 0 setups. Doesnt that work here too?


    Intel has implemented TRIM in RAID, but you need to be using TRIM-enabled SSDs attached to their 7 series motherboards. Then, you have to be using Intel's latest 11.x RST drivers. If you're feeling frisky, you can update most recent motherboards with UEFI ROMs injected with the proper OROMs for some black market TRIM. Works like a charm.

    In this case, we used host bus adapters, not Intel onboard PHYs, so Intel's TRIM in RAID doesn't really apply here.


    Regards,
    Christopher Ryan
  • 5 Hide
    cryan , April 15, 2013 12:16 AM
    DarkSableIdbuaha.I want.


    And I want it back! Intel needed the drives back, so off they went. I can't say I blame them since 24 800GB S3700s is basically the entire GDP of Canada.

    techcuriousI like the 3D graphs..


    Thanks! I think they complement the line charts and bar charts well. That, and they look pretty bitchin'.


    Regards,
    Christopher Ryan

  • 0 Hide
    utroz , April 15, 2013 12:33 AM
    That sucks about your backplanes holding you back, and yes trying to do it with regular breakout cables and power cables would have been a total nightmare, possible only if you made special holding racks for the drives and had multiple power suppy units to have enough sata power connectors. (unless you used the dreaded y-connectors that are know to be iffy and are not commercial grade) I still would have been interested in someone doing that if someone is crazy enough to do it just for testing purposes to see how much the backplanes are holding performance back... But thanks for all the hard work, this type of benching is by no means easy. I remember doing my first Raid with Iwill 2 port ATA-66 Raid controller with 4 30GB 7200RPM drives and it hit the limits of PCI at 133MB/sec. I tried Raid 0, 1, and 0+1. You had to have all the same exact drives or it would be slower than single drives. The thing took forever to build the arrays and if you shut off the computer wrong it would cause huge issues in raid 0... Fun times...
  • -1 Hide
    hansrotec , April 15, 2013 12:35 AM
    with the crucial m500 960 (599.99 usd) out you could drop the cost by a pretty penny putting in in range of groups
  • 5 Hide
    PadaV4 , April 15, 2013 3:25 AM
    The 3d graphs look sexy :D 
  • 0 Hide
    Aegean BM , April 15, 2013 3:58 AM
    Nice to see "Sky is the limit" once in a while because we're curios and because yesteryear's sky is today's budget rack. (Although in my humble prediction, I can't afford this setup for 10 years.)

    That said, I would dearly like to see the follow up "Fastest Windows Storage for $1000". (I assume it would be RAID 0 of two 500GB SSD.) I picked a grand because it's a common anchor point, affordable today, and anything less is probably just "Get yourself the biggest SSD you can afford on our monthly SSD comparison chart."
  • 0 Hide
    Aegean BM , April 15, 2013 4:23 AM
    SSD RAID 0 is sexy. With HDD being so massive and cheap, I wonder how close HDD can come to SSD in RAID 0. (As if you don't already have an overwhelming stack of requests and ideas of your own for new articles.)
  • -1 Hide
    ojas , April 15, 2013 5:59 AM
    Where's Andrew Ku? Isn't this usually his stuff?
  • 0 Hide
    ojas , April 15, 2013 6:14 AM
    Aegean BMSSD RAID 0 is sexy. With HDD being so massive and cheap, I wonder how close HDD can come to SSD in RAID 0. (As if you don't already have an overwhelming stack of requests and ideas of your own for new articles.)

    They did compare 8 (WD?) HDDs to some Samsung SSDs (830 series, i think).
    Let me see...
    No, 470 series vs Fujitsu HDDs:
    http://www.tomshardware.com/reviews/ssd-raid-array-hard-drive,2775.html
  • 1 Hide
    cryan , April 15, 2013 6:36 AM
    BigMack70lol 32 threads of QD 32That setup is ridiculous... this article was a fun read


    That's equivalent to a total outstanding IO count of 1024. The only reason it didn't go up to 128 threads of 128 QD is because (1) it really muddies up the charts and (2) performance mostly maxes out at TC32/QD32.

    Aegean BMSSD RAID 0 is sexy. With HDD being so massive and cheap, I wonder how close HDD can come to SSD in RAID 0. (As if you don't already have an overwhelming stack of requests and ideas of your own for new articles.)


    The truth is, even with the fastest 15K RPM SAS HDD burners, you still overcome the fundamental issues. When you RAID some HDDs together, you do get much better performance and responsiveness. It's just not anything like the jolt a single SSD can provide.

    Regards,
    Christopher Ryan

  • 0 Hide
    yialanliu , April 15, 2013 6:40 AM
    Very cool to see the performance but I would love to see a test of RAID 5/6 as a much more practical usage of multiple SSDs
  • 0 Hide
    veroxious , April 15, 2013 6:48 AM
    What I would like to know is what the performance difference would be if you stuck that 24 Intel SSD drives in a SAN scenario i.e swopping out 24 300GB 15K SAS drives in an entry level Dell MD3220 chassis with dual-socket sixteen core Intel powered host and 128GB of RAM.................
  • 0 Hide
    veroxious , April 15, 2013 6:50 AM
    Sorry forgot to add.........in a RAID 10/50 config

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