Intel Smart Response Technology and Optane memory cache, are they the same?

[Bouowmx]

I missed the opportunity to ask in AMA on Reddit r/Intel today.

Smart Response Technology and Optane memory cache do essentially the same thing? Cache contents of a storage device? If so, for LGA 1151 chipsets, why is SRT limited, ignoring the C chipsets because they are for Xeon E3 and more expensive, and Q chipsets because they are rare, to H170, Z170, and Z270? Though, all the Skylake/Kaby Lake mobile chipsets (ex. HM175) have SRT.

Would using a SATA SSD to 'accelerate' a HDD, like Optane memory does, be more cost effective to home office users and gamers, the apparent target of Optane memory? Bigger cache at lower price: 120-128 GB SATA SSD, resulting in 64 GB cache (limit in SRT), and 56-64 GB for user) for 60 USD, compared to 32 GB Optane memory for 77 USD. Although Optane memory has better performance than SATA SSDs, would the difference be significantly noticeable for the targeted users?

 

[Ichinisan]

I think Optane is totally different from typical NAND. If I understand correctly, it's more like RAM except that it's non-volatile. Probably doesn't suffer the limited number of write cycles as NAND flash memory cells. Maybe I need to go read up on it again.

 

[BonzaiDuck]

Not sure about your intentions for investigating Optane.

My latest little projects included adding a 960-EVO 256GB M.2 NVME to my system for SSD-caching my SATA SSDs and HDDs, and doubling my RAM from 16 to 32GB to cache my 960 Pro boot-system volume to RAM. Here is my latest dissertation on caching software options -- one in particular:

"SSD caching" thread

No doubt, Optane has some advantage over the other options I know of, but I don't know what it is, don't think it's worth the trouble if it requires newer hardware. Depends on price and size in GB of the device. However, I can say that once you have a totally stable system hooked up to a UPS with enough stellar and flawless RAM, the solution I use myself and the ability to save caches in RAM so that they reload at restart/reboot time is about as good as it gets -- also limited by size in GB. You can also cache SATA HDDs to either an SATA SSD or a caching volume on an NVME, and an SATA SSD to NVME.

But even a 2x8=16GB kit allows you to cache to RAM with a good performance boost, and the software is agnostic or accommodating to multiple controllers, AHCI/RAID simultaneous, HDDs, SDDs, arrays, etc. howsoever you configure it so that it works properly.

Proof of the pudding is stability and no disasters. I've been doing it for three years on four computers including a laptop. Never really had any problem at all with it, but it pays to read the manual and adopt a caching strategy that avoids glitches which I mention in the thread-post.

 

[Bouowmx]

Intel intends Optane to be a new tier in storage hierarchy, between DRAM and NAND flash.

That's an in-depth setup, BonzaiDuck. wow, quite a bit to digest about caching. But I'm exploring low-cost caching:

• 128 GB SATA SSD: 60 USD (last year, got some for 40)
• NVMe likely more than SATA and typically not available in low capacities
• 32 GB Optane memory: 77 USD
• 8 GB DDR4-2666: 70 USD

Optane memory is performant, but the performance increase over a SATA SSD will not be significantly noticeable for a a home office user or gamer, crux of my content. Since Optane memory cache does the same thing as SRT, and Optane is supported on all 200 series chipsets (with Core processor), why is SRT only available for select chipsets? Wearing my tin foil hat, I say the reason has to do with selling Optane memory.

 

[BonzaiDuck]

Intel intends Optane to be a new tier in storage hierarchy, between DRAM and NAND flash.

That's an in-depth setup, BonzaiDuck. wow, quite a bit to digest about caching. But I'm exploring low-cost caching:

• 128 GB SATA SSD: 60 USD (last year, got some for 40)
• NVMe likely more than SATA and typically not available in low capacities
• 32 GB Optane memory: 77 USD
• 8 GB DDR4-2666: 70 USD

Optane memory is performant, but the performance increase over a SATA SSD will not be significantly noticeable for a a home office user or gamer, crux of my content. Since Optane memory cache does the same thing as SRT, and Optane is supported on all 200 series chipsets (with Core processor), why is SRT only available for select chipsets? Wearing my tin foil hat, I say the reason has to do with selling Optane memory.

Are you saying that there continues to be a faux-proprietary factor to it? Or that it's open to use in the same way by non-Intel software?

I haven't really studied Optane in depth, but it was my impression that size was limited -- possibly to 32GB or something. Basically, I think the relationship or ratio of speeds between the caching and cached device influences a bottom limit of size in GB for the former. I was thinking that I could limit NVME cache-volume size to maybe 50GB for an SATA SSD being cached. But everything in my system now has a degree of overkill to it, without gobbling up all the resources I might incline toward using in the future.

Isn't Optane already configurable to a Z170 chipset or same generation? With what I now have, I have no incentive to pursue it . . .

 

[Bouowmx]

Probably the most sensible explanation for limited SRT availability is segmentation, like only Z chipsets for overclocking. Though in my mind, SRT for low-end like B250 would make sense for user experience.

Optane memory is limited to 32 GB because that is the biggest capacity currently available. I don't know if there is a limit of cache size, could be arbitrarily 64 GB, like SRT.

Z170 has no support for Optane memory, for Optane's detriment or no..

 

[BonzaiDuck]

Probably the most sensible explanation for limited SRT availability is segmentation, like only Z chipsets for overclocking. Though in my mind, SRT for low-end like B250 would make sense for user experience.

Optane memory is limited to 32 GB because that is the biggest capacity currently available. I don't know if there is a limit of cache size, could be arbitrarily 64 GB, like SRT.

Z170 has no support for Optane memory, for Optane's detriment or no..

Well, it shouldn't much matter. It seems intended for persistent caching. You can use an NVME M.2 card for persistent caching. But if you can cache to RAM and even restore the cache at boot time with its previous contents, and if you can do it with a $30 software program and lifetime license, Optane is not much to covet at this time.

 

[VirtualLarry]

My understanding, and correct me if this has changed, but Intel is limiting Optane, to supported chipset platforms, and only when coupled with their higher-end "Core" CPU. That means that the Core-derived Pentium and Celeron CPUs are OUT, which is curious, seeing as how Optane performs best with a HDD and Optane, and not an SSD and Optane, and those lower-end systems with Pentium and Celeron are more likely to ship with a HDD, and higher-end Core CPUs are more likely to ship with a real SSD, which essentially renders Optane pointless on those rigs. Quite the product-placement predicament. Maybe Intel will learn, someday.

 

[BonzaiDuck]

In some ways, all this Optane expectation, curiosity and interest seems almost contrary and odd, given the various discussions about ISRT, HyperDuo, RAPID and of course "you know what" that I'm very happy with.

I'm sure Intel has some really great plans or that they thought they had some, but with large RAM kits, NVMe and so forth, they'd have to prove to me somehow that Optane renders my own experiments and accomplishments with Primo totally limp.

Given the market segments you mention and the dilemma you argue, maybe they couldn't see a "bigger picture," but then -- I'm not your mainstream user. PrimoCache users are definitely not mainstreamers. Maybe it's all a matter of perspective.

 

[VirtualLarry]

I think that Intel is really confused about how to "properly" segment Optane (cache) drives, and position them in the market.

They obviously don't have huge production capacity of this type of memory yet, or they're stockpiling it for server DIMMs already.

It's unclear to me how Intel is positioning this.

Clearly, HDD + Optane cache drive is positioned above just a regular mechanical HDD, but where does that stand, relative to NAND-flash based SSD, of likely a much larger capacity for storage? Is Optane cache + HDD supposedly above that, too, or below? If below, then Intel runs into the segmentation issues that I mentioned, relative to what CPUs their software supports for caching with Optane.

 

[BonzaiDuck]

There has to be a simple formula with variables for cache-size, cache speed, source-drive speed and other factors that would allow one to weigh different configurations.

A lot of considerations have a short-run impact as technology improves. For instance, the wattage required of an SATA SSD in a laptop does more to drain a battery than a regular laptop HDD. I could see Optane included in an OEM laptop configuration as it ships. Users aren't going to want much to fiddle with the details. But I've seen thread-posts wherein people with laptops fitted with hybrid-drive Windows installations bork something, and wander among the nettles trying to get it all restored. I'm sure I've seen instances of something like that.

 

[IntelUser2000]

I missed the opportunity to ask in AMA on Reddit r/Intel today.

Smart Response Technology and Optane memory cache do essentially the same thing?

I think we should clear up the OP's question first.

Smart Response Technology or "SRT" just refers to their generic RST driver based caching algorithm.

Optane Memory = Brand name for 3D XPoint based client caching product
Optane = Intel describes it as 3D XPoint hardware + their firmware + unique optimizations for the new hardware

You can, SRT an Optane Memory device. http://www.tomshardware.com/reviews/intel-optane-3d-xpoint-memory,5032-4.html

Performance of Optane Memory + SRT is worse than Optane Memory on an officially supported platform because the latter has Optane specific optimizations. You can see that from the review too. If you read it says the Optane + NVMe(not officially supported) is the one running SRT on Optane Memory.

 

[BonzaiDuck]

I'd have to look at the Optane read/write specs again. It would likely be slower than RAM, but it is persistent. And it would be as fast as contemporary NVMe or more so.

When I built my Skylake, I'd been planning it for a big part of a year, starting off with an X99 plan, then scrapping that to follow with a Haswell Refresh plan and scrapping that. I wasn't keeping up with NVMe M.2 cards. I'd already ordered the parts for Skylake, examining the mobo in greater detail, and picking up the news about the 960 Sammy releases coming soon. But I've been using ISRT and other caching solutions since 2011.

So in my relative ignorance with only casual knowledge of NVMe, it was neither a deal-breaker nor deal-maker for me until after I pulled the main string. I'll have to hear more about Optane or read some excited forum member with posted benchie screenies before I get all hot and bothered about it. Except for the persistence problem which is partially compensated by Primo-Cache's ability to restore RAM-cache contents at restart or reboot, Optane doesn't wick my willie much yet. . . .

 

[IntelUser2000]

I'd have to look at the Optane read/write specs again. It would likely be slower than RAM, but it is persistent. And it would be as fast as contemporary NVMe or more so.

It is lot slower than RAM. With Kabylake you have system memory latency in the range of 70ns. With Optane they are talking about ~10us. Specificially for Optane Memory 32GB they say 7us read and 18us writes.

DRAM is still a much faster medium, but even for Optane, NVMe is a limiter.

While the medium is faster on Optane than NAND Flash, Optane Memory has artificial limitations. First, the 16GB has one channel. 32GB has 2 channels. The datacenter oriented P4800X has seven channels.

Due to that the sequential bandwidth is low. 1350/300MB for 32GB and 900/150MB for 16GB.

The advantage for Optane is on random sequential operations with low QD. Random Read QD1 on CDM gets 150-200MB/s on Optane Memory 16GB while 960 Pro gets 50MB/s or less. Of course the sequential matters too, so they might be a wash overall and 960 Pro faster in some operations.*

Overall, its coupling should be with an HDD. Even the algorithm seems to be better suited for HDD + Optane Memory than SSD + Optane Memory.

*This probably makes it better suited for a caching device than a cheap low capacity SSD. There's also the benefit of a full or dirty drive having zero effect unlike NAND SSDs.

 

[BonzaiDuck]

It is lot slower than RAM. With Kabylake you have system memory latency in the range of 70ns. With Optane they are talking about ~10us. Specificially for Optane Memory 32GB they say 7us read and 18us writes.

DRAM is still a much faster medium, but even for Optane, NVMe is a limiter.

While the medium is faster on Optane than NAND Flash, Optane Memory has artificial limitations. First, the 16GB has one channel. 32GB has 2 channels. The datacenter oriented P4800X has seven channels.

Due to that the sequential bandwidth is low. 1350/300MB for 32GB and 900/150MB for 16GB.

The advantage for Optane is on random sequential operations with low QD. Random Read QD1 on CDM gets 150-200MB/s on Optane Memory 16GB while 960 Pro gets 50MB/s or less. Of course the sequential matters too, so they might be a wash overall and 960 Pro faster in some operations.*

Overall, its coupling should be with an HDD. Even the algorithm seems to be better suited for HDD + Optane Memory than SSD + Optane Memory.

*This probably makes it better suited for a caching device than a cheap low capacity SSD. There's also the benefit of a full or dirty drive having zero effect unlike NAND SSDs.

Thanks. That's a good summary. I must have speed-read or scanned a Maximum PC article on 3D XPoint. But it looks clear to me for the immediate future or the planned life-cycle of my latest (Skylake) PC that it's nothing to hemorrhage your wallet for unless the crest of your PC-building wave is coming this year. I always see this as something like surfing . . .

I'm using a 960 EVO on this box for caching an SSD which replaced a spinner. The remaining spinners are for media and backup, so I don't need to accelerate them. My 2700K system has a 60GB Mushkin SSD for a cache of an old Hitachi F1 Spinpoint. We upgraded the Skylake to 32GB DDR4-3200, and the Sandy has 20GB DDR3. Sooner or later with these approaches together with NVMe drives, you get to a point where the only thing you notice is the difference in benchie scores.

And I'm still wondering what to expect in the matter of that Shanghai software company's future. It's just a nifty tool to work with.