I've got a set of 4 filers, who have all - pretty much concurrently - decided  to start racking up the 'low water mark' consistency points. 

E.g. wafl_susp -w is clocking up quite quickly, giving me as many as 10/sec. 

I think this may have caused my filers to get into a tizzy and crash, but I have two more that are still doing it. (I'm not 100% sure, because once they 'came up' the problem is gone ... for now).

But anyway - these boxes have very little on them - they're not in service yet, so they only have a couple of vfilers and associated vol0s. 
So there is -literally- nothing happening, storage wise. 

The only activity is fairly regular ssh polling for performance stats/usual DFM activity. 

So can anyone give me a suggestion as to how to check why these might be running out of memory? I can stop the performance collection I guess, but that's been running fine for months. (And is also doing so on around another 40 filer heads, so I don't _think_ it's a problem!)

They're 2240-4s, with a single shelf in a HA pair. I have 2 'pairs' (4 controllers) and the two that I've rebooted are fine again. The ones I'm looking at are dev, so I've held off doing so because I'd rather figure out what's going wrong instead.