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Q&A from “SAS vs. NVMe Interface Smackdown” Webcast

24G SAS » Webcasts

The SCSI Trade Association continues to be blown away by the amount of views our most recent webcast titled “SAS vs. NMVe Interface Smackdown,” is receiving. If you want to see what all the buzz is about, you can still listen to it on our YouTube channel here.

We’ve also captured a few of the questions asked and answers given by storage experts Cameron Brett, President of STA and Director of Enterprise Marketing, KIOXIA America Inc.; Jonmichael Hands, NVM Express™ Marketing Workgroup Co-chair and Sr. Strategic Planner and Product Manager, Intel; and Don Jeanette, Vice President of TRENDFOCUS, a data storage industry’s market research and consulting firm.
You got questions? We got answers!

Q1. When do you see 24G SAS coming to market?
Cameron: We could see emergence of 24G SAS products sometime in the first half of 2021. The 24G SAS ecosystem is starting to develop and the first plugfest has already been held.

Q2. I’ve recently seen some news on Value SAS SSDs. Will Value SAS replace SATA?
Cameron: We hope anything will replace SATA. SATA has run its course. At KIOXIA, we have a campaign that we’re running called “Life after SATA” which includes Value SAS SSDs. The easiest way to think of it is you get a single-ported SAS SSD at a much more closely aligned price to SATA. It’s not quite as high performing as your typical SAS drive, but provides much higher performance than SATA. What you end up getting is a lot more performance and reliability for the dollar. That makes it a very easy way to switch away from SATA. It’s typically targeted at single-ported servers. The majority of servers these days come with a SAS connection, whether it’s RAID or just a SAS I/O controller. Value SAS is definitely gaining some traction. We see good adoption coming from the big server industry players.

Q3. Please define the three channels – specifically does “channel” include OEM sales to PC manufacturers?
Don: In the three market segments for enterprise SSDs; One is ‘Traditional Enterprise’, it is the major OEM companies for enterprise server and storage selling directly to the traditional enterprise end markets in the world. Second, tier-one hyperscale companies, you could probably name the 6-7 right off the top of your head that dictate most the volume. Once those are backed out from a unit and exabyte perspective, all of the smaller companies are left over. That’s going to be the channel/aftermarket market: all the lower tier companies that dictate the volume after those first two categories. Again, this relates to enterprise SSDs, not client SSDs going to the PC OEM market.

Jonmichael: If anyone saw the Open Compute Project (OCP) virtual summit this year, there were some presentations by Microsoft, WD and Seagate around this topic. Potentially, PCIe is the ubiquitous interface that many companies have intellectual property around. During the summit, there was a question the hyperscale guys posed to WD and Seagate who are responsible for the majority of shipments of the hard drive in the cloud space: “Could you build a hard drive around NVMe?”. The answer was they already have what that could look like. As I mentioned during this STA presentation, with NVMe 2.0 we already have two different command sets. It would not be very burdensome to the architecture if they wanted to go do that. You could do it in a way that didn’t have any complexity or burden the SSDs whatsoever. In that case, the more the merrier.

Don: I’m always thinking of an interface’s capability, and when I’m thinking about hard drives, I’m thinking of the data rate going from the media to the head and through the connector. Might be a little overkill.

Jonmichael: Yes, they are mostly talking about PCIe Gen3 x1. I think we’re pretty far off – at least 3-4 years away from seeing it in the real world if it happens.

Q4. Why does the EDSFF form factor have so many options?
Jonmichael: There is a misconception that there are many EDSFF form factors. First, they all use the exact same connector. There’s a scalable connector that goes x4, x8 or x16, but they all use the same connector and pin out for the SSD and the variance are really for different purpose-built designs. For instance, the 1U long is for high capacity SSDs, the E.1S is for mid-range capacity TLC and 1U servers. The 1 means 1U server and the E is really design for 2U servers but they all use the same connector and there’s a lot of reuse between them. Not dissimilar from today where you have a low-profile add-in card, and there’s full-height add in-cards, etc., but they are really the same form factor underneath. There’s planned to be a ton of reuse between the EDSFF form factors.

Q5. What about dual-port PCIe? How will that affect SAS?
Jonmichael: You’ve seen industry leaders in this space such as Dell EMC bringing their top-tier performance enterprise storage arrays like PowerMax to all NVMe already. You have all-flash array vendors like Pure Storage and others doing all NVMe. But these transitions happen slowly. In the enterprise storage space with high availability systems, we’re looking at about three years before NVMe takes over SAS. We’re already seeing it in the top-tier performance and I think it’s only a matter of time before it hits the mainstream.