x99 and z170 problems with dmi in NVMe Raid 0

[Fizzy Coca-Cola]

So i did some looking around.

It appears (SOME!) motherboards are offering RST support for their key-m m.2 slots (for 950 pro etc) to allow raid 0, however DMI 3.0 (z170) connection between PCH (where storage data goes through to get to the cpu) has a hard limit of 3.9 GB/s (less in real world performance). DMI 2.0 in x99 is limited to 2 GB/s, which doesnt even match up to 950 pro read performance.

With the advent of significant SSD improvements in late '16 early '17 (xpoint NVMe SSDs and competitors), will the DMI improve rapidly to handle raid 0 arrays in current and future SSDs? the previous DMI 2.0->3.0 gap is years, and 3.0 just released last year.

Should I avoid an x99 board with the thought in mind of raid 0 NVMe SSDs?

 

[Arcanedeath]

Just run the ssd off the Cpu pci-e lanes instead to avoid the pch bottleneck

 

[bradly1101]

Yeah, you don't want to hang an NVMe drive off the PCH, so I wouldn't pair that x99 board with anything less than a 5930K for the forty lanes it provides.

RAID on these SSD's doesn't seem fully thought out yet at least for Samsung since there's a thread here about their S/W not recognizing the array. RAID0 can be accomplished with Intel 750 NVMe drives though.

 

[VirtualLarry]

I wish I knew why my Samsung SM951 128GB PCI-E 3.0 x4 AHCI M.2 SSD is so slow at 4K32Thrd read/write. It's in a ASRock Z170 Pro4S with newest 3.00 BIOS / UEFI. Installed OS is Win7 64-bit. I tried RST for a while, but it didn't replace the driver used for the SSD, still Microsoft Standard AHCI Driver from like 2006.

I just got 1981 Seq read / 687 Seq write, 239.8 Random 4K32 Read / 209.6 Random 4K32 write.

There's a YouTube video review of this SSD, unsure what mobo, maybe a Z97, and they get twice the score for random 4K32 read in an older version of CDM.

 

[Fizzy Coca-Cola]

I wish I knew why my Samsung SM951 128GB PCI-E 3.0 x4 AHCI M.2 SSD is so slow at 4K32Thrd read/write. It's in a ASRock Z170 Pro4S with newest 3.00 BIOS / UEFI. Installed OS is Win7 64-bit. I tried RST for a while, but it didn't replace the driver used for the SSD, still Microsoft Standard AHCI Driver from like 2006.

I just got 1981 Seq read / 687 Seq write, 239.8 Random 4K32 Read / 209.6 Random 4K32 write.

There's a YouTube video review of this SSD, unsure what mobo, maybe a Z97, and they get twice the score for random 4K32 read in an older version of CDM.

Win 7 doesnt support your M.2 drive properly, get win 10.

 

[VirtualLarry]

Win 7 doesnt support your M.2 drive properly, get win 10.

I'm curious why you say that, because the drive is AHCI. It uses the standard MS AHCI driver. What about that is unsupported?

Edit: And the sequential numbers are fine. I would expect, if it was unsupported, that those numbers would be affected as much, if not more.

 

[bradly1101]

Yeah the version of Windows doesn't matter, M.2 is just a PCIe connection - nothing special or OS dependent about it.

 

[bradly1101]

I wish I knew why my Samsung SM951 128GB PCI-E 3.0 x4 AHCI M.2 SSD is so slow at 4K32Thrd read/write.

Is that the same 951 used for all that video work and has its own dedicated fan? If so, do you think that you are experiencing any wear-related slow-downs? Before you put the fan on it, did its temp. get too high for a while? Or was it always this speed? And is it on CPU lanes or the PCH?

 

[Fizzy Coca-Cola]

Hey Larry, I hope you've worked out your SSD problem!