Zero Availability Index and Slow sever response for User

Hello,

I am using domino server v9.0.1 FP5 on windows 2012 Hyper-V.

I am experiencing zero availability index very often during the day and during that instant the user experience very slow response from the server and their clients hangs.

I have monitored following things during the instant of zero availability

1- Disk I/O-----> Disk I/O is not showing any abnormal hikes

2- Network Response-------> During the event I pinged the server continuously during the event and network response is 1ms to 10ms

3- Domino Server Tasks-------> During the event the Indexer task was consuming around 9% processing and all other tasks were mostly IDLE or using low resources

4- Memory Consumption for both domino server tasks and over all OS----> It was also not at all alarming