Kind of annoying when people spout off what they've been told without any actual knowledge.
Ram drives are very useful, and can speed tasks up several fold, but only in certain situations.
Let me give you two examples.
When running enterprise backup software, you typically have a deduplication function, so that redundant data is only stored once.
Because this is a time critical operation, the efficiency of your deduplication is dependent on your io speed, and how much space has been dedicated for the deduplication cache.
Think if it as a sliding window xraying your data, with data only being considered duplicate if it's duplicated within that window.
The larger the window, the more duplicated data.
The limiting factor on the window size is io speed, since there is more data in the pipe that can't be kept waiting.
So a ram drive allows you to widen this window dramatically, resulting in disk space savings.
In this use case, the ram drive saves expensive enterprise disk space, as that space has to be managed, backed up, etc.
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Use case two - mitigating poor application design.
Quickbooks "Enterprise" uses (or did when I retired it.) a 32 bit database, which means the database can only access 3.5 gig of ram regardless of how much you have.
Additionally, much of the application is hard coded to use the windows directory.
If you need to rebuild a large database, it's not physically possible to do so on a normal drive.
In less extreme situations, it may be possible to do so, but not within your allowable maintenance window.
In this situation, the solution is to load an entire operating system and application into ram, and process it that way, saving the results to non volatile storage.
Need a more common use case?
Any game in which portions of the game must load from disk.
That would be most games.
Cpu freq doesn't rule competitive gaming the way it once did.
It's all about the GPU, and io speed.
A ram drive by definition beats all other drives.
And when you are playing an MMO where your session may be several hours, it's trivial to do a front end load of 10 minutes and a back end save of 2 minutes.