SATA Maximum Throughput on z61t

[zhenya]

Recently installed a solid state drive in my z61t and am trying to maximize performance. Right now the drive maxes out at about 105 MB/s, averaging about 100 MB/s. This is still well below the theoretical maximum speed of the SATA 150 interface. The drive is set to AHCI mode in the BIOS. Is there anything else that must be done to fully utilize the SATA interface?

Thanks.

[Marin85]

What model is the SSD? What OS do you have installed? BTW, there are SSDs tht achieve their optimal performance in compatibility.

[zhenya]

OCZ Apex 120GB on Windows XP 32bit. I have tried compatibility with pretty much exactly the same results.

[Marin85]

Have you set partition alignment for the SSD?

[zhenya]

Yes, partition alignment is set, and I am currently working through the various tweaks on the OCZ forum. At this point the drive is functioning acceptably well - the only problems are occassional stutters (although frankly, it's not much different than I had with mechanical drives). When I benchmark the drive, however, it seems to be hitting the upper limit of the drive controller, and I'm trying to determine if that is just the ceiling that this laptop can handle or if I need to make other configuration changes. I'm hoping for the latter, as there should be another 50% performance available - even with SATA 150.

[Marin85]

Even with SATA-150 it should go up to at least 120 MB/s reading (according the OCZ specs it maxes out at 160 MB/s). A side note: even if you find the "correct tweaks", it won´t be able to reach 150 MB/s (i.e. the interface limit).

[zhenya]

Ok, my understanding from the SATA wikipedia page was that the 150 MB/s was after overhead was taken in to account.

"First-generation SATA interfaces, also known as SATA/150 or unofficially as SATA 1, communicate at a rate of 1.5 Gbit/s. Taking 8b/10b encoding overhead into account, they have an actual uncoded transfer rate of 1.2 Gbit/s, or 1,200 Mbit/s. The theoretical burst throughput of SATA/150 is similar to that of PATA/133, but newer SATA devices offer enhancements such as NCQ which improve performance in a multitasking environment."

Anyhow - even 120 MB/s would be a nearly 20% improvement over what I'm now seeing.

One other thing - in Device Manager under my Primary IDE Channel Advanced Settings it shows 'Transfer Mode: DMA if Available' 'Current Transfer Mode - Not Available.' I think when I was running under compatibility mode it showed 'Current Transfer Mode - ATA 5' or something similar. Does this current setting sound correct for SATA?

[Marin85]

Just a side note: 1200 Mbit/s=150 MB/s

[zhenya]

I know. Where is the 'at least 120 MB/s' figure from your previous post taken from? I'm still hoping for 150 MB/s. (Also, why did you say that it won't reach the interface limit?)

[Marin85]

There is actually nothing specific about this number, it´s was rather picked randomly Actually, I had also in mind that the real tech specs of the SSD could be in fact around let´s say 120 MB/s (acceptable difference in specs for an OCZ MLC SSD...), so there would be some minor tweak that needs to be applied to reach the maximum, or it is just that XP cannot handle this particular model so good. I have seen a few cases where both Vista and XP reach very high throughputs on SSDs, but the Vista ones are simply higher... Since the (theoretical) limit is around 150 MB/s, other things like controllers (or even cpu ) can lower it - by how much, I can´t say, hence another reason to have randomly picked 120 MB/s.