Samsung SM951 AHCI SSD Performing Poorly At Sub-4k File Sizes

[Mako88]

Hmmm, comparing my newly installed SM951 to scores that are posted on various review sites, and it's performing extremely well in the larger file read/writes, nearly identical to others results, but is getting killed in 4k tests...particularly high que depth 4k tests.

It's about -45% lower than the marks should be in the following specific test spots:

Anvil 4K QD16 : Scores 98,473 IOPS, should be around 150,000 IOPS

ATTO - Everything Below 64.0 K: Scores are off on 0.5 through 64.0 by -30 to -50%, then magically catch back up to 100% where they should be by 256.0...odd)

CrystalDiskMark 4K Q32T1: Scores 337.2/308.8 while it should be around 512/450

AS SSD 4K-64Thrd: Scores 400/361 while it should be around 680/360

ASS SSD Copy-Benchmark, "Program": Scores 417 MB/s with a 3.37 s duration, should be around 780 MB/s with a 1.80 second duration

HD Tune Pro 5.50 4K random multi (32): 47202 IOPS, should be around 100000 IOPS

I'm running Windows 7 on an MSI X99S Gaming 7 (4x lanes)...any particular OS setting or something that should be checked that would affect the smaller file transfers?

It's strange because what I've listed above are the only areas within each benchmark that were off, the other 20+ measurements within those tests were spot on. Wonder what I'm missing.

Here are the full benchmark results: http://i.imgur.com/iKny0sj.jpg

 

[Berryracer]

Which IRST driver are you using?

 

[Mako88]

Which IRST driver are you using?

None that I'm aware of, it gives me grief whenever I try to install it: "this platform is not supported" yada yada.

How do you get around that barrier?

 

[Berryracer]

None that I'm aware of, it gives me grief whenever I try to install it: "this platform is not supported" yada yada.

How do you get around that barrier?

Sounds like you didn't even connect the SSD to an Intel Controller to start off with if the IRST driver is not installing. This could be a major performance issue.

 

[Hellhammer]

Which IRST driver are you using?

Intel RST doesn't currently support PCIe drives, so the SM951 uses the native Microsoft AHCI driver.

OP, try disabling C-states in BIOS as well as any PCIe power saving settings. Then rerun the tests and see if that makes a difference.

 

[Berryracer]

Intel RST doesn't currently support PCIe drives, so the SM951 uses the native Microsoft AHCI driver.

OP, try disabling C-states in BIOS as well as any PCIe power saving settings. Then rerun the tests and see if that makes a difference.

ohhhhhh thanks for this, never knew that.

 

[Mako88]

Intel RST doesn't currently support PCIe drives, so the SM951 uses the native Microsoft AHCI driver.

OP, try disabling C-states in BIOS as well as any PCIe power saving settings. Then rerun the tests and see if that makes a difference.

Thanks hammer, good suggestions. I disabled c-states and double-checked the PCIe power to make sure they were ok. No difference unfortunately.

Over the last few days since I first tested the drive, the results have gotten worse, now it's really off with file sizes below 64.0KB. Like -60 to -75% slower than it should be compared to multiple benchmark sites with identical gear. Which is maddening, because with the larger file sizes it's performing exactly where it should, around 2000 MB/sec. But look at the 0.5, 1.0, 2.0, 4.0, and 8.0 results, all are awful, should be 200-300% higher:

And here are normal results for the SM951 AHCI, this particular run was pulled from Legit Reviews, but each of the major test sites have numbers close to these:

The results on the smaller file sizes are shockingly bad on mine.

 

[razel]

Since the rest of the benches are up to snuff, then I wouldn't worry about one particular bench. Chances are your drive is tired. Keep in mind how fast these SSDs are. 2500MBs means you can fill up your 512GB drive in less than 3.5 mins. Takes longer to take a piss and wash your hands sometimes. Think about it 1TB in 7 mins! A 1TB HDD with 100MBs takes almost 3 hours!

 

[Mako88]

Since the rest of the benches are up to snuff, then I wouldn't worry about one particular bench. Chances are your drive is tired. Keep in mind how fast these SSDs are. 2500MBs means you can fill up your 512GB drive in less than 3.5 mins. Takes longer to take a piss and wash your hands sometimes. Think about it 1TB in 7 mins! A 1TB HDD with 100MBs takes almost 3 hours!

If only it were that simple.

The vast majority of day-to-day files (OS, games, etc) are below 128KB in size...hence the slow down is absolutely being felt and it's no good. It's actually performing slower than my years-old Intel 510 SSD, which was never a speedster to begin with.

Anyone else have any suggestions?

 

[razel]

If only it were that simple.

...the slow down is absolutely being felt and it's no good.

Anyone else have any suggestions?

It is simple if you want it. You actually feel the difference? If you do it might be time to take a break. Seriously you need to give you brand spanking new SSD time to breathe and catch up with itself.

2.5GB sequential per second is not like miles per hour. When you need 128K of data and your sequential is 2.5GB you are not getting it in 2500000/128 of a second. So even with a SATA II SSD at .6GB, you will get the 128k of data at roughly the same VERY fast amount of time. It's only when you need 2.5GB of data per second that the .6 SATA II SSD will take 4-5 times longer.

Latency is closer to miles per hour (or travel time) for a car. Sequential speed is maximum amount of boxes that car can carry.

I still wouldn't worry about it. 2.5GB is nuts and balls and everything else in between crazy fast!!! Just use it and enjoy the time you save.

 

[Redstorm]

You might be seeing FUA IO where the driver is writing directly to flash to avoid the cache.

http://forums.anandtech.com/showthread.php?t=2429885

 

[coercitiv]

Thanks hammer, good suggestions. I disabled c-states and double-checked the PCIe power to make sure they were ok. No difference unfortunately.

Just to exclude any CPU bottlenecks, have you tried running the benchmarks after setting Windows power profile to High Performance?

 

[Ketchup]

What BIOS are you running? There are a couple that list "compatibility" improvements on these.

 

[alteringNate]

Question to OP: I have just installed the SM951 AHCI in my Gigabyte GA-Z97X-UD5H and I cannot get any benchmark to clock anything beyond 700MB/s.

I completely agree with Razel, that speed is already insanely fast, however it is just strange that all over the place I'm seeing reports of users having 1200 to 2200 MB/s. Plus with my 840 EVO I was already at 450MB/s so honestly the price difference for this M.2 is not really worth it if I can't pass 700MB/s

I'm on W8.1 x64, and similarly iRST won't install, it's using the base MS driver. I have read that potentially I need to activate RST in the bios and set it to RAID mode however I don't want to use RST, I just want the whole drive to function as fast as possible.

Any ideas?

 

[Insert_Nickname]

Question to OP: I have just installed the SM951 AHCI in my Gigabyte GA-Z97X-UD5H and I cannot get any benchmark to clock anything beyond 700MB/s.

I completely agree with Razel, that speed is already insanely fast, however it is just strange that all over the place I'm seeing reports of users having 1200 to 2200 MB/s. Plus with my 840 EVO I was already at 450MB/s so honestly the price difference for this M.2 is not really worth it if I can't pass 700MB/s

I'm on W8.1 x64, and similarly iRST won't install, it's using the base MS driver. I have read that potentially I need to activate RST in the bios and set it to RAID mode however I don't want to use RST, I just want the whole drive to function as fast as possible.

Any ideas?

If you've installed it in the mainboard M.2 slot, you're limited to PCIe 2.0 x2 bandwidth. In which case ~700MB/s sounds about right.

What you need to do is move it to one of the PCIe 3.0 slots provided by the CPU. You might need an adaptor to do that, but they're pretty cheap.

 

[alteringNate]

If you've installed it in the mainboard M.2 slot, you're limited to PCIe 2.0 x2 bandwidth. In which case ~700MB/s sounds about right.

What you need to do is move it to one of the PCIe 3.0 slots provided by the CPU. You might need an adaptor to do that, but they're pretty cheap.

Thanks - but how do you know that? I could not find that written anywhere, just these two bits from their product page:

"M.2 for SSDs drives with up to 10 Gb/s data transfer"
and
"1 x M.2 PCIe connector
(Socket 3, M key, type 2242/2260/2280 SATA & PCIe SSD support)"

In any case the 10GB/s would be false advertising and technically impossible if it is limited to PCIe 2.0 x2, no?

I will grab a PCIe adapter, I have plenty of x4 (or greater) slots open. Any suggestions on brands or are they all pretty much the same?

 

[Insert_Nickname]

Thanks - but how do you know that? I could not find that written anywhere, just these two bits from their product page:

"M.2 for SSDs drives with up to 10 Gb/s data transfer"
and
"1 x M.2 PCIe connector
(Socket 3, M key, type 2242/2260/2280 SATA & PCIe SSD support)"

In any case the 10GB/s would be false advertising and technically impossible if it is limited to PCIe 2.0 x2, no?

Not at all. You're confusing bit with byte. 10Gb/s (note the lower-case b) equals 1.25GB/s or 1250MB/s (upper-case B). Which when allowing for bus overhead (8/10B encoding) tops out at 1000MB/s.

What can I say... marketing perhaps...

I will grab a PCIe adapter, I have plenty of x4 (or greater) slots open. Any suggestions on brands or are they all pretty much the same?

Such adaptors are completely passive. So there will not be any practical difference. Be sure to check your mainboards manual as to which slots are fed from the CPU, and also be aware that plugging the SSD into a CPU provided slot will cut bandwidth to the GPU to PCIe 3.0 x8. Not that there is much performance penalty (1-2% tops) doing that.

 

[fb02521]

Is this drive fully compatible with Windows 7?

 

[alteringNate]

Not at all. You're confusing bit with byte. 10Gb/s (note the lower-case b) equals 1.25GB/s or 1250MB/s (upper-case B). Which when allowing for bus overhead (8/10B encoding) tops out at 1000MB/s.

What can I say... marketing perhaps...



Such adaptors are completely passive. So there will not be any practical difference. Be sure to check your mainboards manual as to which slots are fed from the CPU, and also be aware that plugging the SSD into a CPU provided slot will cut bandwidth to the GPU to PCIe 3.0 x8. Not that there is much performance penalty (1-2% tops) doing that.

OK thanks for the explanation. However I'm still curious how you know that the onboard M.2 slot runs at PCIe 2.0 2x? Why would they limit it when they know that an adjacent PCIe slot can run at 3.0 4x? I understood by design that the M.2 occupies the PCIe lane at which it's located, but maybe I misunderstood something else...

Plus the 1000MB/s that you reference is faster than the 700MB/s that I get...

 

[vailr]

Intel RST doesn't currently support PCIe drives, so the SM951 uses the native Microsoft AHCI driver.

More detailed Intel RST version information is needed for clarification.
The motherboard bios includes an RST firmware, and Windows requires a corresponding Intel RST device driver.

Latest versions of each:

Intel Raid Rom (Orom / SataDriver) Version 14.0.0.2209
http://www.station-drivers.com/inde...ge-Technology-(RST)-Version-14.5.0.1041-Beta/

Intel Rapid Storage Technology (RST) version 14.5.0.1041 Beta
http://www.station-drivers.com/inde...ge-Technology-(RST)-Version-14.5.0.1041-Beta/

Some M.2 compatibility information:
https://www.ramcity.com.au/blog/m.2-ngff-ssd-compatibility-list/189#comment-2002130242

 

[vailr]

Question to OP: I have just installed the SM951 AHCI in my Gigabyte GA-Z97X-UD5H and I cannot get any benchmark to clock anything beyond 700MB/s.

Try "UEFI BIOS Updater 1.24":
http://www.majorgeeks.com/files/details/uefi_bios_updater.html
Note: does not work with BIOSes from X99 chipset mainboards.

 

[larryccf]

........... Any suggestions on brands or are they all pretty much the same?

i;ve been using the addonics expansion adapter card http://www.addonics.com/products/adm2px4.php

At $19 + shipping, i'm hitting full specs, speed wise. Be leary of adapter cards that show a heatsink - they're a joke - do some research and you'll find there are complaints or reports of a gap between the "heatsink" cover and the PCIe SSDs, and if you think about it, there has to be allowance for the differing thickness of the SSDs, whether 128, 256 or 512 GB

the addonics can be had on amazon for $27 shipped, and one other item - if you compare the addonics card and the Lycom DT120, they're identical, except for pricing

fwiw

 

[Insert_Nickname]

OK thanks for the explanation. However I'm still curious how you know that the onboard M.2 slot runs at PCIe 2.0 2x? Why would they limit it when they know that an adjacent PCIe slot can run at 3.0 4x? I understood by design that the M.2 occupies the PCIe lane at which it's located, but maybe I misunderstood something else...

Plus the 1000MB/s that you reference is faster than the 700MB/s that I get...

Its quite simple really. The Intel H/Z97 PCH only has two General Purpose Ports (GPP) that can be configured for either SATA or PCIe. Mainboard manufacturers use those two for the PCH provided M.2 slot.

As for bus throughput, you'll never see the full theoretical speed the bus is capable of. As its... theoretical... :biggrin: (I'm sorry, just couldn't resist)

The motherboard bios includes an RST firmware, and Windows requires a corresponding Intel RST device driver.

Intel RST drivers only apply to drives connected to the PCH. There is no support for drives plugged into the CPU directly.

 

[jor8888]

x99
Turbo M.2: delivering next generation M.2 Gen3 x4 performance with transfer speeds up to 32 Gb/s