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Bringing SSD Performance to the DIMM form factor

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Re: Bringing SSD Performance to the DIMM form factor

#131

Post by Dylan16807 »

solarexplorer wrote: post #88
jpgvm wrote: post #31

Earlier quoted context omitted.

Technically it acts like memory. The dev kit comes with a device driver that makes it look like a block device though, which would be analogous to something like NVMe.

IIRC a single DDR3 slot can address max 8GBytes. So the driver will have to map the 400GB Flash into this window.

DDR3 supports 8gbit chips and you can shove 16 onto one DIMM, so 16GB. But that leaves 3 address lines unused for column select. Theoretically they could make a 64GB or 128GB board. Also LRDIMMs can go up to at least 64GB.

DDR4 directly supports 512GB, and also throws away three potential column address bits.

Re: Bringing SSD Performance to the DIMM form factor

#132

Post by hrjet »

maxidog wrote: post #77
sebastianavina wrote: post #73

Earlier quoted context omitted.

if ram and permanent storage becomes the same, in instance, you wont need to "open(" a file, just to point to the memory location of it.

Is that fundamentally different from http://en.wikipedia.org/wiki/Memory-mapped_file ?

I was just thinking about this the other day. Yes, a memory-mapped-file is different, because the API is still that of a file. The memory mapping is just a behind-the-scenes optimisation.

Re: Bringing SSD Performance to the DIMM form factor

#133

Post by digikata »

valarauca1 wrote: post #114
digikata wrote: post #78

Earlier quoted context omitted.

But raw flash writes on the order of 1-2 milliseconds, so the 5 microseconds must be the latency to write to a ram cache inside the stick. I wonder what the latency would be for a write larger than the buffer. For that matter, how large is the buffer?

If you read the source you will see that no independent benchmarks have been done yet.

The article did update with a benchmark link comparing a couple of models to a fusion io card.

http://www.percona.com/blog/2014/08/12/benchmarking-exflash-...

So the 95%, write latency is 1-1.5 msec for one model, and 2.5-3.5 msec for another model. Maybe representing SLC/MLC flash?

95% read latencies are maybe 350 or 250 usec.

Re: Bringing SSD Performance to the DIMM form factor

#134

Post by shkkmo »

avn2109 wrote: post #118
j_s wrote: post #99

Earlier quoted context omitted.

I will archive this thread to save this: > 1TB of non-volatile storage [...] Most average consumers won't use all of that

Seriously this. Don't worry, Windows 11 will certainly require 1TB to run MaterialAeroMetro 2022. The only thing worth debating is whether the GUI design pendulum will have swung between Flat/glossy an even or odd number of times by then :p

Windows 11? There isn't going to be a Windows 11, the version after 10 will be Windows 20, or maybe just Windows Cloud.

Re: Bringing SSD Performance to the DIMM form factor

#135

Post by ars »

icebraining wrote: post #76
tfb wrote: post #43

Earlier quoted context omitted.

> There's also the fact that it won't lose its data on power loss. Does this mean that for software to take full advantage of this, the software will need to be updated to account for it? For instance, Redis loads data into memory from disk upon starting, but if something like this 400GB SSD is available as memory (and say for instance, 300GB is in use by Redis), wouldn't it make sense for Redis, upon starting, to ju…

Not really; we already have suspension (to RAM and to disk), this can work just like it. For the userspace software, it'll be like it never stopped running.

No, that's not correct. This is MUCH MUCH slower than RAM.

You would not use this to replace RAM, but rather have a second section of memory for persistent data.

Re: Bringing SSD Performance to the DIMM form factor

#136

Post by Dylan16807 »

j_s wrote: post #99
sillysaurus3 wrote: post #84

Earlier quoted context omitted.

Spectators may want to archive this HN thread for posterity, because I suspect nacnud will have the last laugh. (Nacnud's comment is currently sitting at about -3 points.) It's unlikely that future technological advancements will give malware authors more tools to work with? That seems unlikely, if history is any indication. Imagine when you have 1TB of non-volatile storage which operates at speeds close to those we…

I will archive this thread to save this: > 1TB of non-volatile storage [...] Most average consumers won't use all of that

By cutting out the part about speed you've grossly distorted the quote. Yes, people will hang on to lots of data. But for the vast majority of files there is absolutely no need to access them faster then, oh let's say 1gbps with 1ms latency.

I'm sure people will find something to do with it but I'm having a very hard time thinking of situations where you want massive amounts of RAM and also need to be very power conscious or wary of power loss. Certain types of database, perhaps? I wouldn't imagine HPC worries much about power loss. Video game textures don't need to be nonvolatile.

For most purposes you can keep shoving in DRAM and SSDs until you have enough space.

Re: Bringing SSD Performance to the DIMM form factor

#137

Post by IgorPartola »

This is sort of the opposite of the RAM-based battery backed drives [1]. I can see this being immediately useful for things like large database servers: instead of re-priming caches on reboots you just have them already warmed up. You can also suddenly have a whole lot more "RAM" at the cost of its speed.

I do have a hard time picturing what this will look like if it was as fast as traditional RAM. If I can store everything in RAM, from the OS binaries, to the running processes, it certainly has a kind of elegance to it. Lots of microcontrollers already act this way: all your hardware has an address in a single address space, be at a hardware port, ROM, RAM, NVRAM, etc. However, I wonder how the modern UNIX OS will work with a system like this without block devices at all. I wonder if what it'd do is actually just use RAM disks, and years from now we'll still be doing this the way we do double emulation of the TTY. That'd be kind of sad since it means we can never get away from the concept of old block devices.

On the other hand it's damn convenient to be able to just append to a file and not have to worry about reallocating it. This means that perhaps all we'd need is a filesystem that's designed to work over RAM rather than over block devices.

[1] http://en.wikipedia.org/wiki/I-RAM

Re: Bringing SSD Performance to the DIMM form factor

#138

Post by jacquesm »

justincormack wrote: post #62
luma wrote: post #40

Earlier quoted context omitted.

HP is already working on this with what they're calling "The Machine". They're writing a new OS around the new storage technologies with the understanding that it might not make sense to separate RAM from disk pretty soon here. They've also suggested that they'll be porting versions of Linux and Android to this platform. Of course, all of this is pretty marketing heavy and not a lot of details have been released, so…

I am not sure it is even a real project. I tried to find anyone working on it and failed. Nice story though.

It's very much real but I'm not sure if I agree with the basic premise. 'Regular' operating systems have gone through a whole slew of storage changes relatively unscathed, what it is about faster persistent storage that you could not encapsulate the same way we did with memory mapped files I do not understand. Obviously HP is far from stupid (or at least, its scientists are) but for now I'm on the fence if this is going to be a true revolution or just the needle moving a bit further to the right.

Real revolutions in OS tech have for the last decades come from the keyboards of large institutional users and from hordes of smaller ones. Even IBM has pretty much acknowledged that. So we'll see if HP will be able to keep the door locked to someone doing a linux device driver for their new hot hardware or to add a few calls to the kernel that enable an application to use this tech.

The same has happened to infiniband (fast networking for clusters and storage) and tons of other esoteric hardware including shared memory between physically disjoint machines (DSM).

Re: Bringing SSD Performance to the DIMM form factor

#139

Post by jacquesm »

toyg wrote: post #113
sillysaurus3 wrote: post #84

Earlier quoted context omitted.

Spectators may want to archive this HN thread for posterity, because I suspect nacnud will have the last laugh. (Nacnud's comment is currently sitting at about -3 points.) It's unlikely that future technological advancements will give malware authors more tools to work with? That seems unlikely, if history is any indication. Imagine when you have 1TB of non-volatile storage which operates at speeds close to those we…

I downvoted nacnud because it's such a generic statement, you could post it to almost any thread. Net neutrality? "Think of the potential for viruses to spread!" iWatch? "Think of the viruses you could have on your watch!" New JS framework? "Think of the attacks it could enable!" Yeah, of course, everything has security implications and some technologies even more so, but unless one explains them and states how they…

Then you did not properly grok his comment in the first place.

Re: Bringing SSD Performance to the DIMM form factor

#140

Post by jacquesm »

StavrosK wrote: post #124
pbhjpbhj wrote: post #115

Earlier quoted context omitted.

I'm with you I got my first 1TB HDD last year thinking it would last a few years. Nearly full now. Why? Because with all that space available I've changed how I use disk space - why throw stuff away. Also that I've moved to a higher grade camera and moved to consuming video stored on HDD rather than from discs. When we're creating fully immersive 4D environments in place of holiday snaps then I imagine we're going to…

> Because with all that space available I've changed how I use disk space - why throw stuff away. Funny, I'm the opposite. With all this bandwidth available, why keep stuff?

Because storage availability is under your control but bandwidth+remote storage availability is not. In other words, you could lose your remote stuff + access to it.
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