Node restarts or double failures due to “Process blocked for x sec, max block time is 2.500000 sec.” In this case, x is the length of time the process was blocked, and it was greater than 2.5 seconds.
The HADB Node Supervisor Process (NSUP/clu_nsup_srv) tracks the time elapsed since the last time it did some monitoring work. If that time duration exceeds a specified maximum (2500ms by default), NSUP concludes that it was blocked too long and restarts the node.
NSUP being blocked for more than 2.5 seconds cause the node to restart. If mirror nodes are placed on the same host, the likelihood of double failure is high. Simultaneous occurrence of the blocking on the mirror hosts may also lead to double failures.
The situation is especially likely to arise when there are other processes—for example, in a colocated configuration— in the system that compete for CPU, or memory which produces extensive swapping and multiple page faults as processes are rescheduled.
NSUP being blocked can also be caused by negative system clock adjustments.