I’m reading 32gb total memory and 1gb swap. I like that ratio but I think you had an out-of-memory problem, not a swapping problem. It’s been 12 hours since your initial post so is the server more relaxed now?
Something won’t let go of memory which could be a problem during or after your next backup. One reason for having plenty of memory is surplus elbow room.
Maybe this is helpful:
I tend to agree with the ‘zero-swap’ opinions, especially for high memory systems like yours. Not that getting rid of swap will free up memory, it’s just one less thing to worry about.