pietrop

Crucial MX300 - bad performance

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Hi all,

I've got 6 Crucial MX300 525GB connected in JBOD mode to a ServeRaid M5110e in a IBM X3650 M4 server. Configuration of the system:

 - 2 x Intel Xeon E2690 2.90Ghz

 - 96GB DDR3 1333Mhz

 - Ubuntu 16.10 Server, Kernel 4.8.x

I've done some intensive testing using the fio configurations found on your website. The workloads are 4k random reads and 8k random reads/writes (70% mix). Instead of doing parallel jobs I decided to go for 1 job per test and tested 1 to 32 IO Depths.

My purpose was to find the best OS settings for those SSDs in a md software RAID10 configuration.

I tested single disks, RAID10 and RAID0 in order to find if performance scales, and it does, so md isn't an issue.

Now I'm stuck at the single disks performance because they average at a maximum of ~40k IOPS. Probably I miss something in the whole picture but shouldn't those disks reach 80k to 90k IOPS?

Am I testing in the wrong way or the problem resides in driver or bad system configuration? I decided to buy them based on your reviews of the 750GB version, but never overpassed 40k iops... 

 

Thank you all

 Pietro

Edited by pietrop

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That RAID card you are using will never be as fast as a dedicated HBA or an Intel chipset connecting the SSDs to a SATA bus. So much of that bursty speed you see in a review would be lopped off by the 9260-based RAID card.

What long term workloads will you be running on those SSDs? Since you did see our review I'm curious what pushed you in the direction of this particular model to purchase. It didn't response well at all in any of our server workload profiles.

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Hi Kevin,

thank you for your response. I was in need of a bunch of affordable SSDs that reaches the performance showed in your tests (80k to 90k IOPS each). This machine has been built for testing and development with databases and computational software and I was on a budget (Italy and UK black friday + ebay coupon).

I posted a parallel thread on the HBA forum where you just answered. Probably the RAID controller is the bottleneck. I ALWAYS observe half the expected IOPS on single SSDs in my tests at any IO Depth and both on 4k and 8k workloads compared to your benchmarks and the ones I found on the net.

Here is a graph showing the average IOPS for the 4k and 8k fio workloads available on this website. The tests where run before over-provisioning. The OP process improved low IO Depth performance, which now are a little bit faster, but never overpassed the ~40k IOPS limit.

 

ssd_iops.png

Edited by pietrop

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Out of the gate the RAID card vs HBA (or the Intel chipset that we test with in our consumer platform) will chop away quite a bit of performance. Sometimes 2-3x.

The 12Gb/s LSI based cards do have an HBA mode that can offer much higher performance than what you are seeing through that older RAID card. Even better is a straight up LSI 9300-8i HBA and sticking with software RAID in the OS.

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Will I be able to connect the 12Gb/s connectors to my 6Gb/s expander (backplane) simply using the right cables? Are the two interfaces compatible or should I buy a 12Gb/s backplane?

PS My purpose is to use md (Linux software RAID), which is really fast from what I've seen.

Edited by pietrop

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Does your backplane actually have a SAS expander chip in it? Or is it just a backplane?

If the backplane is just a plain backplane then using the correct cables should work. If your backplane actually has a SAS expander chip in it, then you would need to make sure your new HBA is compatible with the SAS expander chip in the backplane, and you would be limited by connection speeds supported by the backplane's SAS expander.

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