Hi Giles Are you using FVE 7.1 or earlier? I remember the VMware Storage Latency Report could only be run for individual datastores.  Starting in FVE 7.2, you should be able to run it against all datastores. Keep in mind the report will only show datastores with latency. FVE 7.2 should be available in few weeks.  I hope this helps, Gaston.   
Hello, I would like to create a report from the VMware Storage latancy template, but have the ability to report on multiple datatstores. Do I need to create a new report template to do this or do I need to create a Service with all the datastore in that and report on that service? The only option I seem to get a selecting only one datastore.   Many thanks in advance. Giles Ogram
Custom report for multiple Datastore latencies