Great question. Our monitoring solution doesn't check that frequently so the length of downtime can't be determined down to the minute unfortunately. However, I can tell you that I recently saw a high RTA for a VM for 30 seconds at the very least. It could have been going on longer. And by high RTA, I mean 500 ms in a gigabit network. I am running a very crude ping side by side between this VM and the management interface of it's host to see if I can see some correlation but nothing yet. However, I see occasional jumps in the response such as this:
64 bytes from hostname (10.12.1.10): icmp_seq=2664 ttl=128 time=0.366 ms
64 bytes from hostname (10.12.1.10): icmp_seq=2665 ttl=128 time=0.373 ms
64 bytes from hostname (10.12.1.10): icmp_seq=2666 ttl=128 time=0.312 ms
64 bytes from hostname (10.12.1.10): icmp_seq=2667 ttl=128 time=0.327 ms
64 bytes from hostname (10.12.1.10): icmp_seq=2668 ttl=128 time=101 ms
64 bytes from hostname (10.12.1.10): icmp_seq=2669 ttl=128 time=0.297 ms
64 bytes from hostname (10.12.1.10): icmp_seq=2670 ttl=128 time=13.9 ms
64 bytes from hostname (10.12.1.10): icmp_seq=2671 ttl=128 time=0.331 ms
64 bytes from hostname (10.12.1.10): icmp_seq=2672 ttl=128 time=0.403 ms
In theory, that is high for an internal data center network. Just in my short time, I see no correlation between high RTA on the VM and on the management interface of the host. Still digging. 