How to calculate how much data each search-head-clustering is searching
What do you mean by that? What problem are you trying to solve?
I have 7 search heads in one cluster->(Splunk-Enterprise ) and 5 search heads in another cluster(ITSI) i want to know how much memory is consumed by each cluster for a searching for every hour.
The Monitoring Console should have something close. Look at Resource Usage: Instance. If it doesn't fill the need exactly then copy it from $SPLUNK_HOME/etc/apps/splunk_monitoring_console/default/data/ui/views/resource_usage_instance.xml (using the CLI) and modify it to suit.