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Intel RST RAID performance.

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April 11, 2011 7:01:03 AM

I suggest that you write a article about the performance of the Intel Rapid storage system with a RAID5 array. On the intel website you get the impression that it will perform really well. It does when it comes to read speed but write speed is extremelly slow and is for all intents and purposes useless. The Intel forums are full of people trying to get an answer out of Intel but to no avail.

I am used to installing and setting up RAID-systems and recently installed a RAID5 system with 6 disks on a brand new p67 motherboard. Installation and the setup was very easy and actually better than many other RAID-competitors (3ware,LSI, Adaptec etc).

My biggest gripe by far concerning Intel Rapid Storage Technology is the abyssmal write performance on RAID5!

I am aware of the problem with alignment issues affecting performance and hence use 512k sector drives (2TB Hitachi 7k3000). Write cache is enabled etc.

With this setup I am currently getting around 450-490 MB/s read speed which is great, however my write speed is around 30-40 MB/s?!

I have 16GB of RAM, a 2600K running at 4,5 Ghz and I would assume that this could perform the parity calculations needed for writing?

When performing write tests the CPU never goes above 10% so it is not lack of computing power.

This is about a third of the write speed of a single harddrive?! When searching this forum and looking on some other tests on the internet other users seem to be getting between 5-80 MB/s write speed (depending on the number and type of drives).

This is totally subpar and not at all acceptable, how can Intel boasts about all the advantages of Rapid Storage Technology with this beeing the reality of RAID5 performance?!

Nowhere on the site are there any performance figures quoted, the reason for this is quite obvious.

Also apparently the RAID10 implementation is inferior too (due to them not optimizing how they write and read from the striped drives within each set).

Most people respond to these posts that you should get a hardware raidcard. I have however done that several times before but was curious after reading all the marketing stuff on the website. If Intel can not deliver acceptable RAID5 write performance it should state that on the website so people do not have to waste time installing this crap and beeing dissappointed. This really drags down my impression of Intel as a serious actor in the storage business. Be honest and clear Intel, people will always appreciate that. Look for instance at what OCZ is doing in regards to their SSD-drives. My company will by OCZ SSDs from now on. State on the website that RAID5 write performance will be really low and if that is needed Intel Rapid Storage is not suitable.

Read speed seems to be on par with what I see from my highend controllers so if you are mostly contrained by readspeed Rapid Storage is great.

The reason it is slow is not due to lack of CPU horespower to calculate paritydata rather a really shoddy implementation.


Regards.
April 11, 2011 2:02:28 PM

Thanks for the suggestion. I'll definitely pass it on. :) 
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September 12, 2012 4:27:14 AM

I thought I was having this same issue. The Intel raid initializes the drives but gives you the option to start using the RAID array immediately. During initialization the performance absolutely sucks but after, this thing screams! I am getting 550MB read and 150MB write using ATTO Disk Benchmark. Unfortunately after Truecrypting the volume I am getting a little over 350 Read and right under 100MB write.
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September 12, 2012 4:36:19 AM

Wanting to post some other numbers. I bought an Asrock 990FX with the FX8150, board which has 6 Sata 6GBs ports that can be used for RAID 5. Then bought the Intel Z68 with the i7-2700k which has 4 Sata 3GBs and 2 Sata 6GBs ports usable in RAID 5. I have 6 Hitachi 7K3000 2TB drives with 512k Byte sector size. On the Intel board I have the option to enable drive caching, on the AMD board I did not and I at least know the difference in the read was about 350 average read for AMD, 550 average read Intel.
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November 3, 2013 3:58:36 AM

Bump. I think an indeep analysis about Intel RST is overdue.

I have quite some experience in developing RAID solutions (and no, not assembling RAID but developing drivers and optimizing the backend in embedded solutions and let me tell you, whatever you know about "HARDWARE RAID", they are all software deep inside and they all use the same methods, no matter the costs) and even I must say: Intel RST is a two-faced creature: RAID0 is always fine, RAID1 is always fine, RAID10 is always fine. But RAID5 is a mystery.

If you manage to make RST-RAID5 run fast then it uses VERY little CPU and runs VERY fast. E.G. running it natively on Linux by mdadm --assemble --scan && mdadm -I /dev/md/imsm it always runs blazzingly fast with very little CPU. Also on some Windows machines it runs very fast, e.g. my P35/ICH10 runs 3x1500GB with 220MB/s read and 180MB/s write. Also a P55 with 3x2000GB runs at 280MB/s read and 200MB/s write, never using more than 2-3% of a single core, no matter what scenario.

On the other hand there are sometimes problems with some other systems with incredibly low write performance when the cache runs full, usually around 20-40MB/s and depending on the size of your RAM- and SSD-cache this usually shows up after 2-30GB of writing data, e.g. right now a Z87 system with 3x3000GB+60GB SSD-Cache.

Just to make clear, Linux with native RST-RAID is always fast, Windows RST RAID0+1+10 are always fast, Windows RST RAID5 read is always fast, just Windows RST RAID5 write is sometimes extremly slow.

I do suspect unalignment problems with RAID stripe size and NTFS cluster size and many more. Sometimes the problems go away after an insane amount of try and error. Getting true info from Intel about the problems seems as promising as squeezing water from a rock (citing another victim of RST problems) and while I am quite sure there exists a good reason which I could find with some time I simply do not have access to the necessary hardware for the required time of several weeks to put some benchmarks and analysis on this bitch. In two cases I have been able to make the problem go away after reinstalling and reformating several times and chosing different RAID-stripe and NTFS-cluster sizes. Most systems seem to run good at RAID-stripe 64k and NTFS-cluster 4k, no system seems to run good at RAID-stripe 128k and some run good at 64k/64k or 32k/16k or 16k/16 or 16k/4k. Very elusive results.
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November 4, 2013 6:16:12 AM

We don't seem to have an overwhelming abundance of information on the subject available to our users, not as much in the other areas. Would you guys be willing to author a tutorial about RAID5? I'm sure it would be quite helpful to users. Additionally, if it was useful enough (and easy enough to read), we could toss it up on Tom's IT Pro or TH as a community article.

What are your thoughts?

-JP
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