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DDRamDisk: RAM disk, a disk based on RAM memory chips

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Re: DDRamDisk: RAM disk, a disk based on RAM memory chips

#22
post #20

Having this in M.2 format would make an awesome swap drive for a bunch of devices out there with undersized soldered RAM.

Just to mention it: There exist M.2 to PCI-Express adapters, and also Thunderbolt to PCIe (and Thunderbolt to M.2 to PCIe.)

Some examples here: https://egpu.io/best-egpu-buyers-guide/

(M.2-to-PCIe are under “M.2/NGFF” in the table I think.)

Re: DDRamDisk: RAM disk, a disk based on RAM memory chips

#23

Where I work we handle massive nd2 time series images often reaching hundreds of GB. From image capture at the microscope to segmentation and some post processing steps the biggest bottleneck for us is disk speed. I'd be very interested to see how fast our pipeline is with one of these at our disposal.

If your processing is full of random I/O, this would be the right tool.

Re: DDRamDisk: RAM disk, a disk based on RAM memory chips

#24

Isn't it more simple to buy a MB with 16 RAM slots? And more performant?

It’s interesting to consider the difference.

The price grows when going to server/workstation motherboards / CPUs.

And: What if you already have a 16-slot motherboard fully populated with RAM? You can add a whole another computer with 16 more slots, but that’s quite a bit of iron, and: How best to connect the two? Does there exist an interlink that shunts data between two computers at full PCIe 4.0 x4 speed? Or x8? And how to control processing on the second computer?

I’m sure there are bigger motherboards yet, but afaik it always comes with further components – say, more physical CPU sockets that need to be populated?

There are probably situations where this hardware is the simple way of doing a job.

Also: If the current motherboard already has a unused PCI slot, then it’s kiiiiind of a free return on investment to use that bandwidth. By putting the existing I/O controller to use.

Re: DDRamDisk: RAM disk, a disk based on RAM memory chips

#26

Isn't it more simple to buy a MB with 16 RAM slots? And more performant?

This board has a battery, so the memory is retained for up to a year between reboots. So you can copy your data to it once, and it's super fast.

Though, using ordinary RAM and initializing it before use, copying say 128GB is only going to take a few seconds these days.

Re: DDRamDisk: RAM disk, a disk based on RAM memory chips

#27
Astera Labs have a commercial version of this that works through CXL (assuming you have a platform that supports it :-)), meaning you can actually have load/store access to the memory instead of using the block interface.

https://www.asteralabs.com/applications/memory-expansion/

Re: DDRamDisk: RAM disk, a disk based on RAM memory chips

#28

Isn't it more simple to buy a MB with 16 RAM slots? And more performant?

This board has a battery, so the memory is retained for up to a year between reboots. So you can copy your data to it once, and it's super fast. Though, using ordinary RAM and initializing it before use, copying say 128GB is only going to take a few seconds these days.

The point was more in line of RAM bus being faster than PCIe.

Re: DDRamDisk: RAM disk, a disk based on RAM memory chips

#29
post #5
post #2

I don't have a use for this, but I enjoyed the detailed write-up! In these days of fast SSDs, are there still uses for a RAM disk, beyond extreme niches?

SSDs have wear which will lead them to eventual failure. Wear land nearly as bad as a few years back, but you can still only write to a cell for only a limited amount of times. If you're constantly writing data to your disks, you may need something that doesn't die. I would personally go with a "normal" RAM disk in this case, but CPUs only have a limited amount of RAM and memory channels available. Complex operations…

ECC is supported, see the following comment: https://ddramdisk.store/2023/01/19/the-ddr4-pcie-x8-lady-has...

Re: DDRamDisk: RAM disk, a disk based on RAM memory chips

#30

Not a new concept. Has been done a few times before. The use cases are very small, and getting smaller these days as motherboards accept larger and larger memory modules. https://www.newegg.ca/gigabyte-gc-ramdisk-others/p/N82E16815...

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