Abstract question about Hardware RAM disks

[AdonisReed]

Long ago (2006ish) you used to be able to buy battery backed up RAM disks. These things typically a PCI card, that housed a few sticks of RAM, had a built in battery that would last for 48 hours or so, and presented to the OS exactly like a hard drive... Now I know you can create a "ram disk" using software with your regular memory, but this was different because it could survive reboots and indeed you could even take it out of a computer and stick it in another one. The advantage obviously was speed, these things were faster than any regular HD, I think they would be even faster than the fastest NVMe Gen 4.0 disk by a mile, the limitation was strictly the speed of the connection...

So what happened to them? Can you still get them? or was the size of the volume just too small to be useful?

Another thing I was wondering is, why can't a regular NVMe SSD disk be combined with some RAM and a battery to allow for really fast writes... writes are sent to RAM, which is battery backed so they can't be lost, then written to the SSD... that would make writes insanely fast.

I'm not seeing anything like this, so I guess there is either a technical or commercial reason not to do it, but I don't know what.

Thoughts appreciated

[GAAF]

The industries that used it by-in-large switched to SSD cache systems rather than trying to save the ram itself. And write speeds are already fast enough for general consumers using nvme that trying to do the thing you described doesn't really make a ton of sense.

[|Cayn|]

The speed with RAM disks and Nvme now won't make much of a difference for regular use and almost unnecessary. Companies now use Nvme or SSD as is safer than ram disks on the long run.

[[MPGH]arunforce]

The first question:

2006: ram size (fast) > storage size (slow).
2020: storage size (fast) > ram size (fast).

Theoretically, they're redundant, just one is significantly more faster for the tradeoffs. Hopefully one day storage will be as fast as RAM, and we won't need it.

The second question:

Using RAM as a cache before writing to a SSD doesn't exactly work. RAM and storage have to go through the CPU to talk to each other, RAM doesn't persist infront of the SSD like a cache. So why write to ram and then write to the SSD with another round trip through the cpu? There's no point. It's up to the application to decide whether you need to store it in memory or storage depending on your needs.

[AdonisReed]

Long ago (2006ish) you used to be able to buy battery backed up RAM disks. These things typically a PCI card, that housed a few sticks of RAM, had a built in battery that would last for 48 hours or so, and presented to the OS exactly like a hard drive... Now I know you can create a "ram disk" using software with your regular memory, but this was different because it could survive reboots and indeed you could even take it out of a computer and stick it in another one. The advantage obviously was speed, these things were faster than any regular HD, I think they would be even faster than the fastest NVMe Gen 4.0 disk by a mile, the limitation was strictly the speed of the connection...

So what happened to them?https://snaptube.cam/https://9apps.cam/ Can you still get them? or was the size of the volume just too small to be useful?

Another thing I was wondering is, why can't a regular NVMe SSD disk be combined with some RAM and a battery to allow for really fast writes... writes are sent to RAM, which is battery backed so they can't be lost, then written to the SSD... that would make writes insanely fast.

I'm not seeing anything like this, so I guess there is either a technical or commercial reason not to do it, but I don't know what.

Thoughts appreciated

thank you my issue has been solved