
The Intel Optane Memory (SSD) Preview: 32GB of Kaby Lake Caching - 2bluesc
http://www.anandtech.com/show/11210/the-intel-optane-memory-ssd-review-32gb-of-kaby-lake-caching
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xoa
Might be somewhat niche, but this is looks to be a near perfect match for SLOG
usage in ZFS based storage schemes where a certain amount of synchronous
writes are important. SLOGs don't need much raw space or massive throughput,
they need low latency and reliability (including of course persistence in the
case of power loss). Traditionally this has been handled either (suboptimally)
by flash drives (preferably SLC) or by battery backed RAM drives, which are
extremely expensive and have their own potential failure modes. This though
looks almost exactly right and could become the new basic answer. In fact it's
cheap enough and good enough that it may make ZFS users who previously decided
it wasn't cost effective enough to bother with even if some gains were
available reconsider.

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loeg
Something to consider for SLOG (or other journals, e.g., bcache) is that write
endurance of the Optane 16-32 GB models is pretty poor. You might want a
bigger Optane (or SSD) as a writeahead log / WB cache not because you need the
capacity, but because you need the write endurance.

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xoa
Absolutely an important consideration, and it certainly depends on the use
case. The IOPS also isn't remotely as high as the larger models or a ram drive
(though SLOGs can be striped for more). But it's $44/$77 whereas the P4800X
starts at ~$1500 and something like the DDRdrive X1 (4GB RAM/4GB SLC
NAND/power backing) is ~$2k. For a lot of individual applications (and
remember, sync behavior can be set per dataset and SLOGs are assigned per
pool) even the limited write endurance will be sufficient for a significant
period of time, and even if these initial Optanes were burned through within a
single year it could still be dramatically more cost effective: at these
prices we're talking decade(s) of yearly replacements before equalling the
cost of one higher end drive. Also consider where we are on the development
curve for this tech. This is effectively 1.0 of XPoint technology, so it's
reasonable to expect significant improvements in capacity/$, performance, and
so on over the next few years, which in turn means it may be desirable to
cycle them relatively fast anyway.

What I had in mind wasn't that these would be replacements for existing
solutions used for high sustained intensity applications directly making
money. Those are covered by ram drives or striped SLC already (and perhaps the
P4800X series soon). I was more thinking the Optane Memory might provide a
solid route for experimentation by a new class of users given the capex of a
few pizzas. A lot those cases are going to be relatively low sustained
intensity, but with burst performance still desirable. Heck, for forty someodd
bucks some might go for it just to do some profiling and get a feel for what a
separate ZIL would do for them at all.

If anything a significant limiting factor right now may simply be the relative
availability/preciousness of M.2 slots in deployed home/soho appliances,
servers and workstations.

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loeg
Yep, those are all good points. Thanks for sharing your thoughts :-).

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kristofferR
LinusTechTips just tested this (video is not on YT yet though), and their
benchmarks show that it's only really useful as a HDD cache. When used as a
SSD cache the only real difference can be found in synthetic benchmarks.

It's unfortunate that it's only available for Kaby Lake, since I imagine that
most people in need of a HDD cache run much older systems.

~~~
kristofferR
Here's the video I talked about:
[https://www.youtube.com/watch?v=xgTYSsaNU_A](https://www.youtube.com/watch?v=xgTYSsaNU_A)

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arielweisberg
Intel has a feature where you can use one of their SSDs as a cache. It's
fantastic. Except they limit you to 64 gigs no matter what the size of the
SSD. Incredibly annoying since what I need cached doesn't remotely fit in 64
gigabytes.

I get to experience lovely things like performance falling off a cliff when
stupid programs preallocate 30-40 gigs at a time. If I could use the rest of
the SSD it would be no problem.

What desktop user needs fast write caching for synchronous writes? I mean
really. It's all buffered writes for programs that work right. Cache size is
going to give power desktop users what they need from spinning rust not a
small fast cache that won't even fit a single AAA game. 32 gigabytes is a step
backwards.

And what is with requiring hardware RAID? It really makes me think all the
rapid response stuff is just for marketing.

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wtallis
> "And what is with requiring hardware RAID?"

Intel doesn't really do hardware RAID, just software RAID that the motherboard
firmware has a compatible implementation of for boot purposes. There is one
hardware feature that Intel relies on for RAID or caching involving NVMe
drives: the PCH can remap the PCI registers of NVMe drives so that the NVMe
drive is only accessible through non-standard interfaces on the SATA
controller. This prevents non-Intel NVMe drivers from binding to the NVMe
drive and getting in the way of their caching or RAID. It's a hardware hack
Intel created to work around poor software architecture.

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tpetry
Optane menory is a really nice solution for write-back caches to slow HDDs
(e.g. ZFS Slog, bcache, ...). Or a cache for often-requested HDD blocks which
didn't fit anymore to RAM (ZFS L2ARC).

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throwasehasdwi
Whats the different between this and a regular hybrid SSD/HDD besides being
more expensive and exclusive to Intel? No benchmarks and pretty bad write
speeds(even if latency is low). I bet this would get beat by a SSD/HHD hybrid
for a lot less money.

Queue depth is being hyped but means basically nothing for commercial SSD's
that have battery backed ram cache. The SSD just queues writes until queue
depth is deep enough.

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endorphone
Most SSHDs offer 8GB of flash storage max, and often post numbers that
indicate that the flash storage is mediocre. This will absolutely annihilate
the vast majority (or all) SSHDs. Is it really so much more expensive? $44 for
32GB of high speed caching is impressive.

Extraordinarily few SSDs, even commercial, have battery backed caches (and
those that do often turn into a reliability nightmare), and when they do it
tends to be relatively tiny compared to the scope. Queue depth is profoundly
important in the real world.

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wbkang
One more thing is that every single SSHD ran @ 5400rpm. I ended up buying a
conventional HDD @ 7200rpm and bundled a portion of my SSD with PrimoCache.

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kijin
Yeah, the SSHD offerings from Seagate et al. are atrocious. It's almost as if
they don't want to sell them. Perhaps they're afraid of cannibalizing other
product lines?

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Dylan16807
From what I remember a lot of them don't even use the flash to speed up
writes, throwing away a lot of the potential performance gains.

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searchfaster
Not sure where this will be useful.. Only major advantage seems to be the
super low read latency.

I was wondering if this will be any helpful for a product I am working on, but
as I use mmap for reading our data, don't really see a benefit after the
initial read.

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lallysingh
When you have more data than RAM. There's a cost/performance curve between RAM
-> SSD -> HDD. This is something between RAM and SSD. Makes sense.

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merb
well there are 1tb memory machines not sure if a 32 gb ssd cache would help.

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shadowfacts
The 32GB one from this article is the consumer product with the same Optane
technology as the enterprise/datacenter one. The DC-P4800X (the datacenter
one) has 375GB, 750GB, and 1.5TB variants[1].

So, no, if you have 1TB of memory a 32GB Optane SSD isn't going to make a
difference, but if you have 1TB of memory, you're not the target for the 32GB
consumer version, you're the target for the 375GB+ datacenter version.

[1]: [http://www.anandtech.com/show/11209/intel-optane-ssd-
dc-p480...](http://www.anandtech.com/show/11209/intel-optane-ssd-
dc-p4800x-review-a-deep-dive-into-3d-xpoint-enterprise-performance)

~~~
Dylan16807
> you're the target for the 375GB+ datacenter version

Keeping in mind that that version costs $4/GB, which is about half the price
of adding more RAM. Which means that while it can be good storage for ZFS or a
database, it's still not a particularly effective cache in such a machine.

~~~
merb
well at 1tb memory there aren't that many dimm slots free and some processors
also don't support that much more.

but still what I wanted to say is that it is prolly more useful as a ssd read
cache. and not to have it behind your big memory.

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jrockway
I don't quite understand a few things about this review. One is that they're
using a 960 EVO 250GB as their benchmark SSD, but it's not the best SSD, the
960 PRO 2TB is. How does it compare to that.

The other thing I don't get is that Intel wants to sell Optane drives to
"eSports gamers". Why would they need that? I've heard people on the Overwatch
forums complaining about slow map loading from laptop hard drives... but if
you're playing organized eSports, they're not going to start the match without
you. Matches are paused mid-match all the time for technical glitches. If
you're just playing on your machine at home, that's not really eSports, that's
just playing computer games at home, perhaps with a higher than average
dedication to winning. And map loading time is miniscule with SSDs, so I don't
see the advantage you could possibly derive from there. (It all fits in RAM
anyway, which is cheap.)

I dunno, I kind of see this whole thing as a solution without a problem, at
least in the consumer market.

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wtallis
I only had a few days to test for this initial review, so I picked flash SSDs
that are comparable in price to the Optane+HDD cached setup rather than the
best flash SSD money can buy. The 525GB Crucial MX300 and the 250GB Samsung
960 EVO are both close to but slightly cheaper than the 32GB Optane Memory
plus the 1TB hard drive.

Intel knows that Optane caching isn't an attractive high-end solution; they're
not trying to pitch it against the 2TB Samsung 960 PRO. They'll be coming out
with higher capacity Optane SSDs for primary storage use later this year,
though still sacrificing a lot of capacity for the improved performance
relative to NAND flash.

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Sephr
With this kind of endurance and $/GB, there is no reason at this time to buy
Optane over more RAM, NAND SSDs, and battery backups.

Maybe the next generation of Optane will be worth it, but this generation
certainly is not.

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vbezhenar
I wonder, what would be better for desktop: traditional SSD or Intel Optane
SSD?

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Dylan16807
Define 'better'. In terms of performance Optane absolutely wins. In terms of
performance _per dollar_ it's hard to justify.

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vbezhenar
Better in terms of visible performance of typical tasks (development,
browsing, gaming). I thought of assembling new PC this year, I wanted to go
with Samsung Pro SSD (something like 512G), but now I'm considering to wait
for this new tech.

