AMD AHCI vs MS AHCI - SSD Testing

[RangerXP]

I thought I would share some of my testing results using both the latest AMD AHCI (amd_sata.sys: 1.2.1.292) and MS AHCI (msahci.sys: 6.1.7601.17514 win7-sp1) drivers with my Plextor 128GB SSD drive (PX-128M2S). The results are that the MSAHCI driver was far superior in read operations with slightly imroved write function. For whatever reason - here are the results:

This is with amd_sata.sys:

amd_sata_asssd.jpg
amd_sata_atto.jpg

This is with msahci.sys:
msahci_asssd.jpg
msahci_atto.jpg

What I find most interesting was how the write cache seems to get downgraded to a slower sata speed in ATTO under amd_sata.sys driver that is ultimately what is preventing my drive from running at a higher speed.

All of this was instigated by the fact that my windows experience index for this drive is 7.6. I expected a very high 7.8+ for this drive but have been unable to attain it. WritePrefetch and caching have all be disabled, TRIM/NCQ are active. Seems like it should go a bit faster - if anyone has any ideas?

[oldbrave]

When using the MS driver you're pretty much right on the advertised read and write speeds for that drive ( 420 read and 210 write ).
I'd say keep using the MS driver and be happy with the fact that it works as advertised.

[Mummy]

@RangerXP, What MB you have? ..update its BIOS. Disable "Core C6 State", under cpu configurations and try again.

[RangerXP]

CHV - dunno if I have that option.. but will look. I agree with the MS driver working at advertised speeds. I will be happy with it as such.. but now I am trying to reconfig for RAID.. so will compare when online.

Thanks guys!

[Mummy]

It should be there with new BIOS. at least i have it

[DocLotus]

It has been documented by many others that the MS driver that is automatically installed with Windows is superior to the AMD driver. I ran similar test about 6 months ago and got rid of the AMD driver after finding the MS driver to be much better.

I am running two 120GB OCZ Vertex 3 drives and constantly achieve 500-525MB/s and a Windows7 Experience Index of 7.9.

I also notice that your reads are much faster than the writes, mine are just the opposite. I know that SSD's are supposed to have faster reads than writes but that is not been my experience on these two drives.

I have found no degradation in performance over the last 10 months that the drives have been installed. Looks like Windows Trim is doing it's job.

Cheers;
Doc

[RangerXP]

I just finished the succesful migration of the SSD to RAID. Wow - what a learning curve - worthy of a seperate thread. For now, I am posting the last installment here, which is the performance of the ahcix64.sys driver for AMD RAID support using the onboard RAID ports. While I was able to maintain high seq. read/writes, the overall AS SSD score was quite lower.

SSD results for ahcix64.sys:

scsi_ahci64x__asssd.jpg

scsi_ahci64x__atto.jpg

The lower overall score in AS SSD benchmarks appears to be driven by latency in the controller access times, and slower performance in the 4k writes. On ATTO however, it is superior in the large block read over any other driver, without sacrificing the read rates. This to me is the closest to the advertised speed of the drive.

So now I am left to wonder if that pesky overall AS SSD score of 13 points warrents putting the drive back under msahci? Now that I am able to confirm that the RAID volume will default to AHCI if it is on the chain and not inititalized as RAID.. it may be worth it to retain the TRIM and NCQ functions.. without sacrificing the speed. Thoughts?

[DocLotus]

Like I said, I am getting a very reliable 500-550 MB/s WITHOUT RAID (and 7.9 on the Windows Experience index) using the stock Windows Driver.

Also, one MAJOR problem with RAID on SSD's... THERE IS NO TRIM to keep the drive clean and running at top performance. The performance on my two drives has not varied in over 10 months as TRIM is doing it's job.

I would rather have a non-RAID and a clean well TRIM'ed drive that maintains the same predictable performance than a very fast RAID (at first) that slows down over time because of no TRIM.

Also, RAID can often be a pain in the u-know-what.

But, if it works for you, go for it.

Doc

[RangerXP]

Yes - I am inclined to go back to MS AHCI. I undertand that TRIM and NCQ are only passed to the non-RAID volumes under the Intel platform. Do you know if that is also true of the ahci64x.sys driver? Idealy, I would still have the non-raid volumes being managed under the RAID driver, passing TRIM and NCQ commands to my SSD Boot volume right?

Thanks Doc!

[DocLotus]

No TRIM on AMD with SSD & RAID on Win 7; only on non-RAID AMD systems.

TRIM works VERY well on AMD (no RAID). It does an outstanding job of keeping the SSD's clean. I look at the OCZ Toolkit life expectancy report about once a month and it still says I have 100% of the drive life left. I consider that to be very good as I really push my drives with many re-installs of Windows (bouncing back & forth between Win 7 & Win 8.

One of the tech guys at Directron made an interesting comment to me when I bought the two SSD's; I mentioned that I was going to use them in a RAID Array and he said "Why? SSD's are so blasted fast that most people see little difference in boot and file load times as the rest of the system is not really up to the speed of modern SSD's" I tried them anyway in a RAID 0 Array and was disappointed in the overall performance. He was right!!!

So now I have them configured as drive C (for the operating system) & drive D (for all my documents and FSX).

Also, be VERY sure to completely turn off the Windows Swap file as it can eat an SSD drive for lunch with all the writing to disk; a Swap file will shorten the life of an SSD.

But don't worry, Windows ALWAYS creates a Swap file (usually on disc). If you turn all Swap file off, Windows will create it in memory (another reason to have at least 8 GB of RAM). I have 16GB and my computer runs VERY well with no hang ups or studdering.


Cheers;
Doc