Does RAM Disk persist between rebooting?

I am setting up a video streamer that is going to cache 5-10 seconds of mpeg video and audio on disk. This will then be transmitted. It will be played on receipt. I want to cache my video in memory.

I realize I can do this for free with ImDisk. ImDisk has some W10 and W11 compatibility issues and won't persist a drive on reboot though it makes that claim.

Also, do you know any manufacturers who take actual RAM, put it in a drive, add a disk controller, and make it a plug in USB RAM disk? I realize performance loss of xfer but I am interested in this for another application.

You can create both a volatile RAM disk or a persistent RAM disk. The latter requires an image file to be created where the contents of the disk will be kept between reboots. Please see this article for details: How to create persistent RAM disks with contents preserved between sessions.

I am not sure why you want to persist a few seconds of video and audio though. After a reboot you could simply reinitialise your streaming process and create a new cache. The stream will be interrupted anyway while the system is restarting, so a volatile RAM disk may be better suited for the purpose.

As to hardware USB-plugged RAM disks, I doubt they exist as there would be no enough bandwidth. For example USB 3.0 max transmission speed is 5 Gbit/s = 625 Megabytes/s, while the physical RAM does many gigabytes per second. There used to be some PCI-plugged devices with RAM modules and a backup battery, but as far as I know they are no longer produced.