Troubleshooting SSD RAID-0 Performance

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I'm running a RAID-0 array with 2 Kingston HyperX 120 GB SSDs and getting about 520 / 250 MBs read/write: http://screencast.com/t/OSo7rcxF8TkR

However looking at benchmarks on the web I should be getting close to 1000 MBs for read speeds: http://www.xbitlabs.com/articles/storage/display/kigston-hyperx-ssd-raid0_3.html#sect1

What could be the issue?

 

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Quick update:

With so many drives (see full setup in sig.) I completely forgot that I'm using a PCI-E expansion card for this RAID-0 array as I ran out of SATA ports.

SIIG SC-SA0L11-S1 PCI-Express 2.0 Low Profile Ready SATA III (6.0Gb/s) 2-Port Host Adapter:
http://www.newegg.com/Product/Product.aspx?Item=N82E16816150031

However the card should still support the speed, right?

So I'm thinking its the PCI-E slot that could be an issue. I currently have it plugged into x4 slot, but not sure if it gets routed via North Bridge (correct me if I'm wrong, as I understand not all PCI-E slots are)

Going to try to swap to a space x16 slot to see if it makes a difference.

Anything else that I should try?

 

[XavierMace]

Moving it to a x16 slot won't help, it's only an PCIe 2.0 x1 card, which means it's rated for 500 MB/s.

 

[CiPHER]

The screenshot in your first post seems to be from your Intel controller, not from an addon controller. Also it appears to be a RAID0 on two SATA/300 ports instead of SATA/600 ports. This would be in line with a situation where you use Intel onboard RAID0 on your Asus P6T board with X58 chipset. This chipset does not offer SATA/600 but only SATA/300. Any additional chips - either on the motherboard or via PCI-express addon card - that advertises SATA/600, will not be able to provide full bandwidth and may actually be much slower than your Intel SATA/300 ports.

Buying an addon card for RAID0 usually only leads to lower performance and also lower quality RAID drivers. Because this all concerns FakeRAID - RAID functionality is offered by Windows-only drivers, there is no hardware acceleration available. Only expensive Hardware RAID cards with Intel IOP provide such functionality, but they are more expensive.

For SSDs in RAID0, your chipset controller is the best suited. So i recommend against buying an addon controller and do not recommend using its low quality RAID implementations (Silicon Image, Silicon Motion, Promise, JMicron, ASMedia, Marvell). Intel has the best 'FakeRAID' drivers available and offers a ton of functionality normally only offered by Hardware RAID vendors.

Also, your chipset tends to offer lower latencies, which is most important for your SSDs in RAID0. On top of that, Intel onboard RAID - called RST or Rapid Storage Technology - offers a feature known as Volume Write-back Caching, which further increases performance by buffering writes in RAM memory. This can be very beneficial since in many cases writes happen at RAM speed and the application can continue with its work immediately. So saving a file or whatever just flies into your RAM and you are ready to continue work while those writes are executed on the background. This functionality is normally only offered by Hardware RAID vendors with BBU-protected write-back DRAM memory.

Long story short: do not use add-on controllers but use the RAID functionality offered by your chipset.

 

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Moving it to a x16 slot won't help, it's only an PCIe 2.0 x1 card, which means it's rated for 500 MB/s.

Thanks for spotting that. It completely explains the issue.

What if I was to replace it with a PCIe x2 card like this one:
http://www.newegg.com/Product/Produ...m_re=pcie_sata_adapter-_-16-150-041-_-Product

Would the card above support speeds higher than 550 MB/s ?

 

[Collider]

The screenshot in your first post seems to be from your Intel controller, not from an addon controller. Also it appears to be a RAID0 on two SATA/300 ports instead of SATA/600 ports. This would be in line with a situation where you use Intel onboard RAID0 on your Asus P6T board with X58 chipset. This chipset does not offer SATA/600 but only SATA/300. Any additional chips - either on the motherboard or via PCI-express addon card - that advertises SATA/600, will not be able to provide full bandwidth and may actually be much slower than your Intel SATA/300 ports.

Buying an addon card for RAID0 usually only leads to lower performance and also lower quality RAID drivers. Because this all concerns FakeRAID - RAID functionality is offered by Windows-only drivers, there is no hardware acceleration available. Only expensive Hardware RAID cards with Intel IOP provide such functionality, but they are more expensive.

For SSDs in RAID0, your chipset controller is the best suited. So i recommend against buying an addon controller and do not recommend using its low quality RAID implementations (Silicon Image, Silicon Motion, Promise, JMicron, ASMedia, Marvell). Intel has the best 'FakeRAID' drivers available and offers a ton of functionality normally only offered by Hardware RAID vendors.

Also, your chipset tends to offer lower latencies, which is most important for your SSDs in RAID0. On top of that, Intel onboard RAID - called RST or Rapid Storage Technology - offers a feature known as Volume Write-back Caching, which further increases performance by buffering writes in RAM memory. This can be very beneficial since in many cases writes happen at RAM speed and the application can continue with its work immediately. So saving a file or whatever just flies into your RAM and you are ready to continue work while those writes are executed on the background. This functionality is normally only offered by Hardware RAID vendors with BBU-protected write-back DRAM memory.

Long story short: do not use add-on controllers but use the RAID functionality offered by your chipset.

Ok, just double checked - and you are right!

I have that raid on the onboard Intel controller and not on the add-on card.

Yeah this board has only SATA2 - so basically you're saying I'm stuck with these speeds because of my mobo.

I actually seem to run 2 separate raid-0 arrays on the same controller - in your opinion does this impact performance of each individual array?

Also much thanks for such detailed explanation. Very curious about RST feature, is this something I can enable on my board or would I need another raid controller ?

 

[CiPHER]

Yeah this board has only SATA2 - so basically you're saying I'm stuck with these speeds because of my mobo.

Not only that, but you are also stuck with your SSDs. Because you have SSDs with Sandforce controller, you have very low write performance. These SSDs are advertised with very high performance, but real performance is much lower. This is because Sandforce uses compression and deduplication. Basically, they cheat you by listing very high specs like 500MB/s but only offer 120MB/s write performance per SSD. With two SSDs in RAID0 that would be 240MB/s which is in line with your scores. SATA/600 versus SATA/300 will not change that.

The only benefit you will have with SATA/600 is increased sequential read and multiqueue random read performance. In my opinion, it is not worth it.

So i recommend you keep what you have. Two Sandforce SSDs on your X58 SATA/300 controller in RAID0. Good enough, i will say.

I actually seem to run 2 separate raid-0 arrays on the same controller - in your opinion does this impact performance of each individual array?

If you utilise both the RAID arrays at their maximum throughput you may have slightly decreased performance, but you should have zero performance loss if you use only one at the same time. So basically: no. You can perfectly have multiple RAID arrays on the same controller.

Very curious about RST feature, is this something I can enable on my board or would I need another raid controller ?

It only works with Intel RAID - that is called RST. Other RAID vendors do not provide this feature.

If you have installed the RST drivers you should see an icon in the system tray - next to the clock in the bottom right corner. There you can open the RST configuration screen and it should list your RAID volume and information about it. It should also say Volume Write Cache: disabled (enable now) or something like that. There you can enable this feature. It has a small risk of corruption if you do not shutdown properly. But if you run RAID0 you ought to use good backups anyway so enabling this feature would be recommended if suitable and used correctly. You will not see much difference at all in benchmarks though, but it will impact real-life performance.

 

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Thanks @CiPHER, I think you have a great way of explaining storage in simple accessible terms

I'm going to look into RST drivers and try to install later tonight. I have a few RL workflows that should allow me to gauge the improvement in performance.

Can't believe I never heard of it looks pretty simple to enable - lots of folks have intel controllers so I'm surprised this feature is so underrated.

 

[Capaints]

I'm running a RAID-0 array with 2 Kingston HyperX 120 GB SSDs a

Hi, I see you are running Raid-0 using 2 SSD drives. using the ASUS P6T Deluxe V2 mobo as I am.

my Son the Tech guy I go to for info tells me I can NOT run Raid-0 with SSD drives, they give most people problems....

I need to Re-Install my OS , I'm currently running Raid-0 with 2 WD 150GB Raptors, I like the speed of the New SSD drives But understand I wont get the full speed because of our OLD mobo......

Will 2 Samsung EVO SSD drives run Raid-0 on my mobo ?

Thanks for your help.