Death of SATA III

[Revelation]

Okay, so the title is a bit misleading. I'm in the process of a new build and I have been checking out the somewhat new M.2 format and the NVMe drives.

 

There are pros and cons for both; either one puts you leaps and bounds above the speeds of SATA III SSDs. I'm always looking for ways to increase the "speed" of programs that I use. I remember the first time I fired up an SSD after upgrading from a platter drive... The difference was beyond belief.

 

So on to the "meat and potatoes" of this post.

 

The goal of the new build was to pick the parts to give me that edge I was looking for. I started my research on the M.2 format and NVMe to figure out which one gave me the best bang for the buck. Short story is the M.2 drives will be the choice for the time being.

 

SATA III is limited to 6GB/s in bandwidth which breaks down to 600MB/s in real-world speeds. My current SSD is getting around 550 MB/s read/write speeds and I can't really get any faster than that on a SATA III connection once you factor in overhead.

 

So I started looking at NVMe drives. They utilize PCIe and uses 4 lanes. Each lane of PCIe has 8GB/s which means you have a theoretical bandwidth of 32GB/s. In real-world this should get you close to 4GB/s once you factor in overhead. There are several Intel NVMe drives that are getting in excess of 2GB/s read times and 1.5GB/s write times. As the technology improves, speeds will bump up to the limit.

 

So the big elephant in the room with NVMe is the price. You're typically slightly over $1 per GB with NVMe drives - the quality ones.

 

So in my search I also came across M.2 format drives. M.2 drives can reach the same speeds, in general, as NVMe drives. NVMe will shine in 4k read/writes above the M.2 drives. For all other applications, data access, they are pretty darn close to being equal - again referring to quality drives. So Samsung has the m951 that hits 2.2GB/s read and 1.5GB/s write speeds.

 

For one to hit this level of performance you need to use a PCIe 3.0 connection. Some x99 and the newer z710 motherboards have built-in M.2 drive connectors. You do need to verify if it is a PCIe 2.0 or PCIe 3.0. With the z710's most should be PCIe 3.0.

 

You also need to pay attention to where the PCIe lanes are coming from... In some boards the PCIe lane is shared with the x16 lanes for you GPU. Obviously you don't want that. The documentation is typically good. I have been eyeing the ASROCK Extreme7; by using the M/2 drive you lose x2 eSATA and x1 SATA III ports to get x4 lanes of PCIe for your M.2 drive.

 

The benefit there is it does't touch the x16 lanes for your GPU. So pay close attention if you are looking to squeeze more performance out of your next build.

 

Here is another pro for the M.2 drive - the price... The price is not as good as SATA III SSDs, obviously, but it is far better than NVMe drives at the moment. The Samsung I mentioned earlier is, currently on NewEgg, $399 for 512GB M.2 drive.

 

Now you may be saying, why don't i just get two really good SATA III SSD's and run them in RAID 0.... You are still limited to 6GB/s. You cannot exceed the limitations of SATA III. There are videos on YouTube that get deep in the rabbit hole and explain it much better than me.

 

So here with M.2, read speeds of 2.2GB/s versus 550MB/s with my current SSD. Think of it this way.... Typical 10k RPM drives were hitting 103-350MB/s read speeds. We're not evening talking about more common 7200 RPM drives the most people were using prior to SSDs going mainstream. For those that have made the upgrade to the an SSD, take a second and think about the speed increase from that simply change.

 

The jump in speeds will be 3x or more going from an SATA III SSD to PCIe based SSD.

 

 

 

So in conclusion, I think everyone should be taking a good look at PCIe SSD solutions. As prices come down, they will be more attainable and mainstream. Hope this helps.

[HiJack]

Yes it is 3x faster read/write than the current SATA SSD's but is not bootable. So board vendors need to add NVMe support to current motherboards to provide booting. I will certainly look to add this to my next build but for now the SATA III SSD drives fits fine.

[Revelation]

Actually they are bootable. A driver needs to be added to Win7/Win8, I think Win10 works out of the box.

[Pepec9124]

It would be nice alternative if Intel would stop charging extra for more lanes.

[Pikey]

Actually they are bootable. A driver needs to be added to Win7/Win8, I think Win10 works out of the box.

How does a Windows OS driver make a drive bootable from outside its OS? Sounds counter intuitive.

[remon]

Now you may be saying, why don't i just get two really good SATA III SSD's and run them in RAID 0.... You are still limited to 6GB/s. You cannot exceed the limitations of SATA III. There are videos on YouTube that get deep in the rabbit hole and explain it much better than me.

 

This is wrong. Or badly worded.

 

Also, there is SATA express too.

Edited September 13, 2015 by remon

[xaoslaad]

I can confirm NVMe drives are bootable within Windows 10 without additional drivers. I have an Intel 750 PCI-E NVMe drive and did nothing special to get Windows 10 installed. There was an Intel controller driver I did update after install though.

 

My understanding is NVMe drives are bootable only with Z170 and some Z99 motherboards.

 

One of the big things I like is no more data or power cables to the drive(s). With a modular power supply I litterally just have the 2 motherboard power connectors and GPU cables dince I opted to do away with an optical drive and even install from USB

 

I hope that someday they can get all the power for GPU's over the PCI-E (or whatever) bus so we can just do away with most all of the cables.

Edited September 13, 2015 by xaoslaad

[Revelation]

How does a Windows OS driver make a drive bootable from outside its OS? Sounds counter intuitive.

 

The driver is added to your OS install media. It allows the installer to recognize and utilize PCIe based drives.

[Revelation]

This is wrong. Or badly worded.

 

Also, there is SATA express too.

 

Wrong, no.

 

Badly worded - sure. i.e.:

There are videos on YouTube that get deep in the rabbit hole and explain it much better than me.

 

You know the very text, you yourself, quoted.

 

SATA Express cannot reach speeds of PCIe 3.0.

 

 

Here's a good video explaining the difference, see 7:45 for specifics on RAID0 SATA III versus PCIe drives.

 

[YOUTUBE]kACJLKNOI[/YOUTUBE]

Edited September 13, 2015 by Revelation

[BitMaster]

 

The benefit there is it does't touch the x16 lanes for your GPU. So pay close attention if you are looking to squeeze more performance out of your next build.

.

 

 

 

Unfortunately wrong as any "standard" i7 only has 16 Lanes in total, no way around sharing !

You will have to get a 28 Lane or better Skylake i7 and a totally different motherboard, socket and

maybe RAM.

 

If you have throughput in mind, serious GB/s, there is no way around such CPUs and chipsets but for most users SSD's in general have solved a lot of lag issues, in gaming and other apps as well, for example VMware or 3D-editing where any core is used, the more the better....and those can only work properly if the chipset can deliver multiple streams, the more the faster the better.

 

 

I would rather get 2 SSD's or M2 + SSD and split OS and APP so concurrent access never hinders each other than getting one twice the size and put it all on one. Saying that, I intend to buy another 250 SSD or bigger/better to get my apps away from OS, just cuz of old fashion thinking.

 

Performance wise, I still think a proper Adaptec SAS Adapter with enough 12GB/s SSD in a proper Raid mode blows any M2 off it's socks,...in any aspect but the price tag. Raid-10 with enough (24) SSD and a 100Gbit LAN....what more could I want :)

 

Gbit seems lame in the presence of fast Laptops and Desktops, time to move ahead to 10Gbps NICs and switches at home.

[cichlidfan]

Just don't toss those 'old' SSD's, they make great, pocket sized, external USB 3.0 drives. :)

[whitehot]

although lately I haven't keep myself up to date with knowledge about the various new SSD forms, I seem to recall that one "problem" in exploiting the full SSD bandwidth is the AHCI interface which operating systems like windows use to access them.

 

I may be wrong, but aren't the M2 SSDs still dependant on that interface, while NVMe has a proprietary one that hasn't got the limitations of AHCI? In that case NVMe should be rather more efficient - although I get that the price/space ratio is still much high..

[Revelation]

although lately I haven't keep myself up to date with knowledge about the various new SSD forms, I seem to recall that one "problem" in exploiting the full SSD bandwidth is the AHCI interface which operating systems like windows use to access them.

 

I may be wrong, but aren't the M2 SSDs still dependant on that interface, while NVMe has a proprietary one that hasn't got the limitations of AHCI? In that case NVMe should be rather more efficient - although I get that the price/space ratio is still much high..

 

Not all M.2 drives are of the AHCI variant.

[xaoslaad]

I believe that is correct. For instance Samsung has an M.2 AHCI SSD and are supposed to be releasing a near identical looking NVMe version. To top it off I believe my motherboard has two M.2 slots but only one is NVMe. The other is AHCI.

 

There are also 4x PCI-e cards with M.2 slots for NVMe SSD's if your motherboard didn't have (enough) M.2 NVMe slots...

 

The funny part is that with Skylake and Z170 you get 16 PCI-e lanes from the processor and 20 from the chipset, more than ever, yet you get things like if you use this option or slot it disables this or these others. My 4x PCI-e slot is only 4x if I don't use any of the 1x slots. I think if I used the NVMe M.2 slot 2 1×PCI-e slots get disabled. All this new fun takes lots of bandwidth, which is both good and bad.

[SkateZilla]

My server PCIe8x Drives READ/WRITE AT 2500+MB/sec...

 

SATA-III is a SSD Bottleneck.