Anybody using a RAM Disk?

Also interested to know and also interested to know what you put in it.
 
Sonar cache? windows page file? Anything else?
 
How much do you feel is enough?

That's so funny because I had not heard that term since my Atari days. When I saw the thread title I thought someone had either fallen through a time warp or it was a typo :) 
I remember how fast things worked but it all was lost when you shut down. I always loaded Dr T KCS into RAM Disk. 

i have 2 SSD disk (240GB and 90GB) And also 2 harddisk (1TB and 3TB) i installed windows and Sonar in 240GB SSD
16GB page file (i have 16GB ram) and my frequently used program cacheis in 90GB SSD
1TB harddisk for vsti and other programs
3TB backup and old projects.

Caching can get very complicated very quickly....

HDDs have their own (built in hardware) RAM for temporary caching purposes and helps in giving faster write times for small files, but the size of audio files (especially multiple files being spooled at the same time) rapidly fills that up.

Windows itself operates a cache system where data an application wishes to store to disk is held in RAM by Windows until there is enough of a break in other activity for Windows to actually send the data to a disk. This is usually of the order of milliseconds or a very few seconds at most, and is why sometimes an application will repost a successful safe to the user but if followed by an immediate Windows blue screen the data is lost.

By default Sonar bypasses the Windows caching system. This is partly because it avoids the problem that if Sonar or Windows crashed before data is actually written to disk and Windows caching were active the audio data would be lost. Though in practice that kind of situation generally results in corrupt data or Windows not even realising the data is there on the drive as the necessary indexing wasn't carried out bfore the crash.

Spooling to disk while bypassing the Windows cache at one time also resulted in faster and smoother sequential reads/writes of large files such as multi-track audio. Whether bypassing Window's cache is a speed boost with modern HDDs which have larger buffer caches than their predecessors can only be deternined by trying it and seeing what happens. I've activated the Windows caching in Sonar's preferences before now and seen it load entire projects into RAM the first time they're played then keep the data in RAM. Which gives very fast data throughput indeed so long as you have sufficient free RAM in the first place.

The downside is a Sonar or Windows crash will lose everything recorded that's being held in RAM. Which may not be a situation you'd want to find yourself in.

Which is, of course, also the disadvantage of using a RAM disk. Until what's stored there is saved elsewhere it is virtual data that ceases to exist the millisecond Windows shuts down or reboots. The trade-off being speed for data security.

tlw
Spooling to disk while bypassing the Windows cache at one time also resulted in faster and smoother sequential reads/writes of large files such as multi-track audio.

While this would be true for a single track, won't multi-track audio's tracks each go to different files (which may be far apart if you're unlucky) ?  At least having a dedicated audio drive keeps the head movement restricted to handling only the tracks and not have it also move around for OS and other program activity.

I also haven't used a RAM disk since my Atari days with Dr. T's KCS. However, I've been turning on my new Haswell on a MSI mobo. I have 16GB RAM and haven't seen anything use more than 10 GB, so far. I'd just started looking at the MSI overclock tools and noticed the RD. I've also got a 2 SSDs (boot and BU) with most stuff on the HDD's. I set the RD up and things sure seem to work faster and better. My main motivation was to remove all the junk that the system uses for temp files off the SSD which was plenty fast, but this is much better so far and the OS seems much more responsive. More so than I expected, which is why I thought to post. This seems even better than OC from 3.3 GHz to 3.8 GHz. I'm not likely to use the overclocking but wanted to set it up and learn it now rather than later.
 
While I'd like to try this with my laptop, the OS needs all of the 4GB's it has, so that won't work. But with excess idle memory floating around on the desktop, I figured I'd put it to use. 
 
Even if Sonar doesn't directly use the 'sys temp' directory (which automagically gets pointed at the RD, along with the various browser caches by MSI), OS support and particularly graphics seem much more smooth. I've also noticed that my VRAM on the graphics cards doesn't get used as much either, but that's a game thing. 
 
I'm aware of the downside of RD's, so won't be 'storing' anything on it (other than very temporarily anyway). I already disabled the 'Hibernate' feature and finally got sleep working OK instead. A RAM sized (16GB) hyberfile on my SSD (120) GB is not desirable as it is still just basically a temp working state. Waking from sleep is faster and doesn't use much more power than Hibernate. Of course, I don't disable Hibernate on my laptop, but it doesn't have an SSD and don't much use it on batteries.
 
Good comments above about pagefiles and RD's. If one uses the RD correctly, pagefile use should be reduced, though the pagefile should be on a SSD or HDD and only accessed by the OS when it needs more address space. Pagefiles don't belong on RD's. 
 
While a bit OT for Sonar users, I try to keep things stable across all the constant updates and wondered if others may have tried this. Sonar is one of my more quirky installs and I wouldn't want it to have issues I've created. I'm still pretty bummed about the browser not showing compressed files. 
 
I haven't really exercised Cambridge too much yet, but will probably try some memory intensive stuff.