In general the service time should be below 10ms – if the spike is a brief spike then it is probably nothing to worry about. Navigate to the ASM Diskgroup drilldown (ASM in the toolbar or CTRL-M) – there you can see a history of service time by diskgroup. So you could see if it is a particular diskgroup or all of them – also look at the service time over time. If it was mostly below 10ms and just spiked momentarily then it should be OK – if it was constantly above 10ms then there would be a problem that would need to be investigated.
