Slower than expected performance with RAID / SSD Array

iso50

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I just built a RAID0 array using four (4) Samsung 940 Pro 256GB SSD drives and an LSI MegaRaid SAS 9240-4i RAID controller. Firmware on all drives was updated to DXM04B0Q. Firware on LSI card was updated to latest (2.130.364-1847). Array stripe size is set to 64KB (largest available) and all settings in LSI volume setup wizard were left at defaults. Drive was formatted regularly under Windows 7x64. The card is in a PCIeX16 slot.

CrystalDiskMark results are as follows:



Is this normal? It seems to fall a bit short of my calculations for the potential of this setup. I know this is still fast, but not as fast as it should be I'm afraid. I need at the very least 1.5GB/s for heavy I/O video / audio work. What do you think the bottleneck here is? Any thoughts / tips on setup?

Thanks


 

paul1911

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I'm not expert in Raid array. Nor i ever tried. But i think it is showing the speed of only on SSD. What is normal transfer speed of single ssd?
Have you tried HDTune Pro or ATTO Disk benchmark.
 

iso50

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So do you think it's the LSI board that's causing this? These drives are individually faster than the Corsair Force GT240s that I have yet the Corsairs performed better in Crystal on an Areca-1882i: http://www.tweaktown.com/articles/4284/areca_arc_1882i_and_corsair_force_gt_7_drive_sata_iii_raid_0_setup/index6.html

(see the second result which reflects a 4 drive array) I know the Areca is a better RAID controller, but is it that much better that it would slow down the Samsungs this much?
thanks


 

FireWire2

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What MB do you use with?

Maybe you are using PCI express Gen1 - which is 8x 2.5Gb/s = 20Gb/s. bandwidth

Then 1.4GB is pretty much that your system can do

 

iso50

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I'm on the 16x slot of a Asus P6X58D Premium so should be fast enough (8000MB/s)



 

jemm

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The problem is your motherboard SATA controllers.

The 2 x SATA 6.0 Gb/s ports use Marvell® PCIe SATA 6Gb/s controller, which is crap! :(

The native Intel ICH10R controller supports only SATA 3.0 Gb/s.

In order to optimize the performance you need a motherboard with native Intel ICH10R controller supports only SATA 6.0 Gb/s.

 

noidea_77

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I think it is the way the lsi and the ssd's are working together. The lsi firmware is obviously not optimized for this type of raid. Beside all that: why do you thing you need that high bandwidth for video processing? I don't think there is any video format that needs it and in addition there is no processor that has the power to cut or encode video streams with that speed. Typically video optimized systems use more then one raid array (read from one, write to another) with "simple" sas disks.
 

FireWire2

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No! It is not. You won't have 8GB/s
This is what you have:
3 x PCIe 2.0 x16 (at x16/x8/x8 or x16/x16/x1 mode), also LSI is an 8x lanes card therefore the BEST you can connect is x8

If it's connected GEN 2., then LSI problem, because you have a bandwidth of 40Gb/s

Here is what I suggest...

Test speed of your RAID by adding a single drive at a time, to see where the speed tap off

Check the LSI's BIOS to see the connection, it sounds like it connects at x8 lanes GEN1
 

iso50

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Ah ok... I tried a drive at a time and the array scaled pretty constantly (away from home now so don't have numbers in front of me but will post soon.
thanks
 

iso50

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Thanks I will look into that. I need the bandwidth for a variety of tasks. Shooting 4k with a Red Epic and doing multiple layers in blend modes in Premiere, also do a lot of high track count 24-bit 96K audio production and on the graphic side work with PSBs that get up to 8GB+ so I basically just need one very fast drive for whatever project I happen to be working on. Was running an old array of four Vertex 1 drives and was hitting a lot of walls.
 

iso50

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They're all brand new drives but I did run the Samsung Magician optimization routine on each drive between benchmarks just to be sure.
 

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