I have RAM sticks already lying around, so the cost per GB in this scenerio would be zero. Also, I presume that a SATA interface to store data in RAM might have better performance than the average SSD.
There exist old slow PCI (DDR1 era) cards that do exactly what you expect: https://www.youtube.com/watch?v=bYbCYgYZVT8
There are also some niche contemporary options: https://ddramdisk.store/2022/05/12/meet-the-latest-release/
And in the future there will be very fast options: https://www.anandtech.com/show/16670/using-a-pcie-slot-to-in...
I'm not trying to discourage you or anything, but I think paying $50 for an adapter to run 500gb of RAM slower than a $50 500gb NVMe drive is a bit of a goose chase. Good luck in your search regardless!
It's an interesting question, but I think the circumstances explain why nobody has really commercialized something like this. NVMe will get you 90% of the way for 30% of the price, and it's non-volatile to boot.
I'm going to go out on a limb and say the approach you're considering is practically infeasible OR (best case) would need an oddball/bespoke device to pull this off. I'm not aware of such a device.
Closest you could get is using tmpfs or similar on RAM in RAM slots but it kind of sounds like your existing RAM is electrically/physically incompatible with the system you're attempting this approach with.
It's perfectly fine for some uses, mine included.
> I'm going to go out on a limb and say the approach you're considering is practically infeasible.
To each his own, but I know for a fact that hardware RAM drives were indeed sold in the past, and after posting this Ask HN I've stumbled upon companies marketing them.
https://ddramdisk.store/2023/01/19/the-ddr4-pcie-x8-lady-has...
Yes! I saw that device from elsewhere in the thread. Wondering when it will be available and what use will look like. Also curious about the battery backup and what maintenance looks like on that.
RAM storage has been tried before but was done as PCIe expansion card. It didn’t catch on cause of special drivers, but it only made sense back before NVMe and SSDs were expensive.
SATA is the computer bus interface, while SSD is the generic name for a storage device that more often than not comes with SATA interfaces.
SATA was not a hard requirement, just the one that I felt was the most popular.
> Also, SSDs are much larger and cheaper than RAM.
SSDs are not cheaper per GB if you already have RAM sticks lying around. Nevertheless this is besides the point, if the goal is to have low latency temp storage when you already maxed out on RAM.
The PCIe RAM drive cards were enterprise and super expensive. You could buy a whole computer for one. It is probably cheaper to sell the RAM sticks and buy SSD. As I mentioned, they are super cheap now and cache would only need small one.
Also, setting up RAM drive is a pain. The old cards required special drivers; new ones could probably emulate NVMe. But setting up cache drive and getting programs to use it for temporary storage is annoying. All SSD is easier. There is a lot of experience with using SSD as durable write cache and not as much using disposable temp space.
For those who need speed, buying more RAM is a better way of doing it. If you really need speed, then new computer with more RAM and NVMe is better approach.
In any case, PCIe RAM drives aren’t made anymore. They were a niche at the time and now there is no market at all.