Running Operating System from memory

Assuming SSD's are extremely prone to faliure how economical would it be to load an OS into main memory and run it from there?

I can think I can deal with a few obvious drawbacks (I've survived inside the bounds of a 20gig VM for the last 2 years), but what are the pro's, con's, requirements and cost for running Windows 7 or the latest Fedora or Ubuntu distro strictly from RAM.

Just so there's no confusion, I'm not saying run the OS from a USB stick or live CD. I'm saying, start the computer, transfer the entire OS into memory from a external HD or 'the cloud' or a big memory stick and run it there. When the machine turns off, save the state to the external storage.

Good question, but I think you're missing something - most of the operating system is already loaded into the system's memory on startup. Every programmer in the world knows what the slowdown/bottleneck is in a computer (the disk drive, regardless of it's type, for you non-programmers), so they all load as much as economically possible into the system RAM.

While it's certainly possible to do what you ask, there's really no point, since you have to load the OS from the storage drive on startup, and then re-write it back to the drive before shutting down. Also, once the operating system has been loaded, there's not much that needs to be retrieved from the storage drive (aside from certain system tasks and updates, etc...).

You would see better performance gains by using a RAM disk as a temporary storage area, or even placing entire applications onto the RAM disk and running them from there. What I'm trying to get at is, it's not the operating system that we truly need to run from a fast storage media - it's the applications that you have to load afterwards. Once most operating systems are loaded, there is not much disk access from the OS itself, but rather, the applications you use.

just some ideas. not really well organised. but let's see how far we can go.

admittedly, with the current price of RAM, it becomes a very attractive option for us to run the whole OS from RAM and loading it from harddisk only in the startup (and writing it during shutdown journal-commit style).

the problem is that doing this particular thing is not easy, and given the estimated users that will do that, it will not be very economically sound for software/OS manufacturers/developers to do that.

however for linux it may be an option and one can try to specify the amount of ram available and make a tailor-made OS for it. e.g. 4gb ram edition/8gb ram edition/16gb ram edition, in which 2gb/4gb/12gb are used to load files from the harddisk... etc.