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Comment by marcodiego | Hacker News Reader

What I really want: a very fast volatile SSD. Reason: my notebook RAM is maxed out and I don't want to throw it off; a fast volatile SSD would allow me to use it as a swap device.

Is there such a thing?

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Not volatile, but Optane? Even in the era of super fast pcie4 ssds, the random read times for optane is like 6-10x faster. Fast enough that intel put optane into ram module for persistence.

Plus intel sold nand ssd drives (model H20?) that had a 32gb optane module on board. You can just use the optane for swap and the nand as your main drive.

Also, consumer Optane is hella cheap at the moment. For example, : https://www.newegg.com/intel-optane-ssd-p1600x-118gb/p/1Z4-0...?

Q: ;

I have multiple TBs of SSD currently, how is Optane better at ~118 GBs of stuff... Why would I want this over that?

If you're doing lots of writes it will not wear out the same way an SSD would. Also it's very fast, but these days not as fast as the best NVMe SSDs you can buy now.

Optane has insane write endurance. Speed is good as well. It is expensive for sure but I guess it can be justified for some database use.

I think of optane not so much as a mass storage device, and more as a fast scratch space. The perfect place to put your swap partition, to use as cache in front of slower storage, the scratch space of an algorithm that starts using disk space to save memory, or the intermediate output of your compiler.

Orders of magnitude better wear capabilities and much faster at low queue depth operations

Much lower latency. Optane doesn't have any of the "page" / "cell" bullshit that flash imposes, so there's really no need for buffers at all. Writes just go straight to disk basically, at almost zero latency, NVMe itself imposes much more latency than the actual reads/writes.

There used to be a product called ZeusRAM which was a small (like 8GB) SSD with a matching amount of DRAM. In normal use all operations were done on the DRAM, and when power was lost it would use charge held in a super-cap to flush the data out to the NAND.

Haven't seen any purely volatile drives, though.

The Gigabyte i-RAM from 2005/2006, featured in a LTT video.

So when power is restored it restores the RAM and turns back on like nothing happened?

Correct.

Oh wow lol, this reminds me of Windows Vista days and Microsoft’s ReadyBoost for using a USB flash drive as extra memory for disk caching because it was hammering peoples disks. Good times.

On Linux there is zram which creates a first-priority swap partition that just compresses the pages and keeps them in memory.

It looks like Windows also has memory compression.

I believe that OS X has memory compression turned on by default.

Zram is actually a general purpose block device, you can format it with ext4 and have a compressed RAM disk.

There is also zswap, which is a transparent compressed RAM cache in front of your cache partition. Most distros have it enabled by default, so make sure you don't use it together with swap in zram.

>I believe that OS X has memory compression turned on by default.

It isn't just turned on by default, there is no way of turning it off.

Optane SSDs. 2242 devices should fit in an ExpressCard bay (which is electrically a PCIe slot) but the only adapters are from ThinkMod and the owner of that company has kinda disappeared.

These used to exist, PCI cards loaded up with DRAM, optionally battery-backed. Some talked over a drive interface like SCSI or SATA. I don't know that anyone bothers with them nowadays, since the target was never laptops and it's easy to cram a lot of RAM in a not-laptop.

Here's a list of some: https://en.wikipedia.org/wiki/RAM_drive#History_and_operatin...

Having worked on SSD firmware, that would simplify a lot of the code in the firmware if we didn't have to recover things after a power loss. But I don't think it would improve performance a lot.

Why not just a fast SSD, without being volatile?

Because by being volatile, it could be faster.

Have you actually looked for a fast SSD? Your laptop's SATA/PCIe interface is probably the bottleneck at this point.

Solution, meet problem?

It couldn't, since it would be limited by bus width anyway.

A regular SSD will do. But if your notebook is old, it may only support SATA based SSD, which is not considered fast any more.

6Gb(it)ps of a maxed out SATA III link is still not slow, it's just that the multi-GB(yte)ps speeds of modern PCIe drives is just insanely fast. My TrueNAS box has 3x2 mirrored vdevs of 7200RPM drives and has plenty of bandwidth to handle multiple 4K ProRes streams, the only reason I have PCIe storage (an Optane 800P) on it is because I don't want to waste a precious 3.5" bay for a SLOG device to handle sync writes (VM workloads).

A single board computer with something like a 10GbE connection to your laptop.

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