What is a Ram disk??
No seriously... I want to know....
The word "disk" in "RAM disk" is a bit of a misnomer as there is no disk involved. A RAM disk is essentially an allocation of RAM that is given a drive designation and can consequently be used as storage, just as any regular disk would be. It's contents are only kept while the computer is on in some capacity, as all contents are stored in the computer's RAM. RAM disks are used in exactly the same way any other disk would be, but are faster and smaller in capacity, as RAM is generally lesser in proportion to permanent storage for most computers. The RAM used in the RAM disk is not accessible as standard RAM to the rest of the system until released from the RAM disk.
For example, say you have 16 GB of RAM in your system. If you allocated a RAM disk of 8 GB, your system would then have 8 GB of RAM for application use, and 8 GB of RAM disk storage. :-)
So basicly using your RAM as hard disk space, but I can not really imagine how the data can be kept after the PC is shut down seeing as RAM looses all it`s contents after you shut down... But HOLY SHIT the speeds is pretty insane!!!! But why would you want to do that, 8GB for I.E isn`t really of any use in my eyes...
You're right, all of the contents of a RAM disk are lost after power down. If you put your computer to sleep, the contents would be kept, but eventually every system needs a reboot.
If you need the kind of performance a RAM disk offers, then you could go that route. Really though, they have limited application anymore. Windows is quite good at caching data as it sees fit, and it will do this the first time you load data into memory, which really is no different than loading up a RAM disk. The only difference is, on a RAM disk you have to put the data there, whereas with Windows, it happens automatically. Since you put the data you want on the RAM disk yourself, you have more control over when that happens, so in essence, you are really just pre-caching. However, you could drum up other uses for a RAM disk if you preferred, such as holding temporary files, or browser cache files, or things that are updated often instead of sending those to something with SSD like write characteristics.
Putting your swap file on a RAM disk, while it may sound like a good idea on the surface, is not.
The only thing I run out of a ram disk is my browser and its cache(and the browser itself). Why? simply put it makes things good and fast and has a side effect of limiting writes to my SSD's
It saves to a hard drive on shut down and then reloads on startup.
Please not this DOES slow both the startup and shut down, but my media center is rarely off so its not an issue and even my main system seems to load and save it at a good enough speed.
Another place that ramdisks are used would be POS(point of sale) terminals sometimes as the OS is loaded off the network. This makes for a rather robust system as all data is saved to a server and the systems then selves do not need a hard drive(with SSD's i am not sure if they still do this).