Small follow-up on the NBD connections idea, because I asked internally and it turns out that was not a false lead at all.
The number of NBD connections is capped per host, so 20 per disk is well past what the host will actually hand out, and it is worth turning down whatever else is going on in this thread.
I do not have the exact ceiling yet. I have asked the XAPI side for the real number and I will post it here once I have it, because guessing at it would not help anyone.
@Andrew, that fits your side too as far as I can tell, since you are at 1 and have seen this once rather than constantly.
probain, I will send you an upload link by direct message so you have somewhere to put the logs. I still do not know whether the fallback itself is new this week or simply newly visible, so please do not read anything into my message on that part.
