[Symbiote]

I have 4GiB swapfiles on the cluster nodes I manage, which have 512GiB RAM.

It's hardly used, around 300MiB at present, probably things like the mail daemon. It's been useful to have a very slow node, which I can SSH into (after 10 minutes) and kill a chosen process, rather than a dead/OOMed node. But I think the difference is marginal, and perhaps 512MiB would have been a more appropriate size for the partition.

(Swappiness is set to 1.)

[IncRnd]

We run without swap, and haven't noticed an issue. Did you see any practical benefit to running swap vs not?

[Symbiote]

Other than a couple of occasions where things have run slowly, giving me time to kill the process I choose, I've not noticed any benefit.

Picking a random machine, there is 600MB of swap used. "top" shows where about 50MB is used (Hadoop daemons, systemd bits) but I don't know what the rest is. I guess it could backfire, since logind is swapped out, and I might want to log in on the serial console if the machine is very busy.