This is by far my biggest pet peeve in the space. The "rule of thumb" that you need 2x RAM as swap. Even 10 years ago this "rule" was ancient and useless but it was always a constant challenge educating customers as to why, and that yes - we really did know better than your uncle Rob.

Once a server hits swap, it's dead. There is no recovering it other than for exceptional cases. If you are swapping out, you've already lost the battle.

I tend to configure servers with 512MB to 1GB swap simply so the kernel can swap out a couple hundred MB of pages it never uses - but that's really more to make people feel better than it really being useful at all.