Linux – Do I even need a swap partition with Linux

Ah, I see you have mistaken how to calculate free RAM in Linux.

Linux tends to heavily utilize all the RAM by caching stuff. Instead of reading directory listing from the disk every time, it caches the directory entries in RAM. It caches the frequently used files, so they don't need to be loaded from the disk every time. In case some process actually needs the RAM for its use, the cache will be immediately evicted.

So the formula for calculating the actually used RAM is total - (free + buffers + cached), in your case 3988 - (219 + 165 + 1894) or in other words 3988 - 2278. That is 1710 megabytes of RAM in use and 2278 megabytes of RAM for you still to consume.

Don't believe me? See, your server doesn't even have any swap in use. :)

But of course, a machine crash -- if you mean a hard lock up -- is a strange thing. That really should not happen. I suspect a faulty RAM stick which only gets accessed in case of >2 GB of RAM in use.

Are you hitting swap? Generally, the better solution is to avoid that entirely, or at least make it so that things which are swapped out are genuinely not in active use, so that the speed doesn't matter. Put your money into more RAM.

This is particularly true because while high-end SSD drives may improve performance, cheap ones are very troublesome in this regard.

There is a great article on this week's Linux Weekly News which I highly recommend reading: http://lwn.net/Articles/428584/. The summary is that cheap drives are very, very sensitive to access patterns, and Linux isn't currently designed to match that well. Worse, the drives don't really expose that information in a useful way, so Linux can't necessarily do the right thing. The best best is to use them with their pre-existing FAT32 filesystems, which are factory-configured to match the drive's expectations.

Or else you should buy expensive high-performance SSDs — but only when you're already maxed out on RAM. (And really, at that point, you might strongly consider just getting a newer server which supports more RAM.)