# AHCI and SSD -- Some questions



## Mahlon (Dec 28, 2011)

I installed a Crucial 64 gig SSD to host samples only, and a Highpoint Rocket 620 SATA III card in the 1 x PCIe 2.0 x4 slot on a Rampage Gene II motherboard (which doesn't have SATA III connections btw).

When I test the SSD throughput with HD Tune, the drive gets about 270 Mb/s.
When I test the SSD with AS SSD Benchmark, I get an error message after a few seconds sequential writing to the drive:

*System.IO.IOException: The processs cannot access the file 'G:\AS-SSD-Test42\test.bin' because it is being used by another process.
at System.IO._Error.WinIOError(Int32erreCode, String MaybeFullPath(
at
AS_SSD_Benchmark.Form1.backgroundWorker1_RunWorkerCompleted (Object sender, RunWorkerCompletedEventArgs e)*

Am I supposed to be getting faster results? And could this error be related to AHCI?

When I built this computer and installed Windows 7, I didn't engage AHCI in the bios. Today, I have turned on AHCI in the bios by enabling these two parameters:

Under "Storage Configuration", I enabled "Configure SATA as AHCI"
Under "Onboard Device Configuration", I switched the JMicron 36x ATA Controller to be "AHCI + IDE Mode".

Is this correct? Have I done the correct procedure to enable AHCI? Should it be in AHCI mode to get full performance from the SSD? Or is there something with the PCI-e slot that may be causing the lackluster performace?

Very confused... :? 

Many thanks if you can offer some light on this situation, and whether AHCI should be engaged (and how to do so).

This may not be enough information for anyone to help me. I'm not axactly sure what I'm doing here with this install. Just ask me what other info you need, and I'll try to supply.

Mahlon

System Specs are:
Windows 7 64 bit
Asus Rampage Gene II Motherboard
24 gigs RAM
i7 920
Several hard drives (HDD) and one SSD Sata III drive


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## maraskandi (Dec 29, 2011)

Hi Mahlon, I spent ages trawling the net for info when I was was hooking up my SSD and I found nothing except long forum discussions that gave little clue, eventually someone claimed it wasn't the way to go so I just let it be as I was confused and tired of searching at that point..

I'll be watching the thread in any case, perhaps someone out there has info.


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## Mahlon (Dec 29, 2011)

Thanks for your support, buddy. Yeah, there's a lot of confusing information out there. Right now, my concern is why I'm only getting 266 mb/s throughput. Unless I'm measuring incorrectly.

I reread some older threads and saw that Richard said he was getting around 400 mb/s with the same High Point card and a different, but ASUS, motherboard. I believe he was using the Crucial M4 as well.

What do you use to measure SSD read speed?

Mahlon

p.s. My error message above seems to be related just to that detection program, so I don't think any worries there.


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## rgames (Dec 29, 2011)

A few things:

Which Crucial SSD are you using? With an M4, I was getting about 450 MB/s max. With the C300, I was getting about 390 MB/s.

Second, try using the ATTO disk benchmark - I like it because it tells you how the speed varies with the size of the read. Smaller files will have lower read speeds - the values usually quoted are the max read speeds for the largest file sizes. If your measurement is for a small file size (maybe 4 kB), then your reading might be about right. Also, sequential vs. random read makes a difference, so that might be what you're seeing.

Third, if you have the drive connected to the Rocket card, the BIOS settings shouldn't make a difference: they control the controller on the motherboard, not the one on the card.

Finally, it is all very confusing  Especially the benchmarks: there are so many different ways to measure the performance, it's tough to compare them all. That's why people generally compare the max: the max is generally comparable across systems and setups. The trick is finding the max - point #2 above should help you along that path.

rgames

EDIT: here's a screen capture from my C300 to show you how speed varies with file size. The newer-generation SSD's do better than this.


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## Mahlon (Dec 29, 2011)

Thanks, Richard for your consistent aid in all things circuit board.  

My drive is an M4 SATA 6gb. I'll try the ATTO benchmark and see what I come up with.

Mahlon


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## Ryan (Dec 29, 2011)

I'm just gonna jump into this conversation. I did just install a SSD today with AHCI.
Just some questions: have you installed the AHCI to win7? if not you need to download a reg hack key and use that one before you enable AHCI in the BIOS. 

Here:
http://ryan.tronder.net/reghacks/enableahciinwindows7.rar (http://ryan.tronder.net/reghacks/enable ... ndows7.rar)

There are also some other SSD-progs on my server that are good to have: 
http://ryan.tronder.net/reghacks/

hope this help. 
Best
Kai-Anders Ryan


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## rgames (Dec 29, 2011)

Been a while since I set them up so I checked my SSD's - the controllers are configured as AHCI.

I never had to do any registry tweaks so I'm not sure why that would be necessary. I'm using the default Win 7 drivers.

rgames


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## Mahlon (Dec 29, 2011)

I did go into the registry and made sure that msahci start was set to a value of "0". 
And Windows 7 seems to load fine when I switched AHCI in the bios. So I think everything's ok there.

Mahlon


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## Mahlon (Dec 29, 2011)

Richard, when I try to run ATTO Disk Benchmark on the Crucial M4 drive, I get an error message which says "unable to write file". Any ideas on that?

It works fine on the HDD in my system, but not the SSD.

Thanks,
Mahlon


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## rgames (Dec 30, 2011)

Can't write to file? That's weird - you definitely have some type of config problem.

Can you copy files to the drive?

Also, which driver are you using for the controller card? I'm pretty sure I just used the default Win 7 driver - I don't recall installing one...

I don't know what "msahci" does but did you try changing it to 1? Seems like it would be 1 if you want to use the AHCI config.

rgames

EDIT: also, you got a write error with the AS benchmark, too. That error message basically says that the program can't write to the file because something else is using it - sounds kind of like some type of driver problem, like somehow the driver is getting in the way of the code. So I'd have a look at drivers.


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## Dracarys (Dec 30, 2011)

I'm a little confused since I'm not too hardware savy.

If you're using your SATA lll ssd in a SATA ll port on your mobo, then 266 mb/s seems about right.
If you're using a PCIe 2.0 SSD, then depending on what SSD it is you can get massive reads.


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## Mahlon (Dec 31, 2011)

Richard,

Everything seems to be fine now. I realized that I had chocked the drive full of samples, so many so that ATTO had no where to write, thus the error. Removed some samples and did the ATTO Benchmark and the drive seems to be about what yours achieved, I think.

The info I used for enabling the windows drivers for AHCI, I got from here, among some other sources, too:
http://www.sevenforums.com/tutorials/61869-ahci-enable-windows-7-vista.html?ltr=A

Thanks for your help.

Casalena,
The SSD is connected to a PCI-e card which runs at SATA III speeds.

Here's the ATTO Result:

Mahlon


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## rgames (Dec 31, 2011)

OK - that makes sense 

Looks about right - ~400 MB/s max on the Marvell controller (in the Rocket card). I got about 450 MB/s using the onboard Intel controller on another motherboard. I'm not sure that makes much difference in the sample streaming world.

rgames


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