I cannot seem to find this counter anywhere within DFM and have activated all special counters and have created custom views in Performance Adviser. I understand NetApp uses the 4k block for processing at the disk after it leaves the front-end ports, but need to determine what my I/O block-size mix is that hits my array. NetApp indicated the counter should be located under the "Target" counter, but seen nothing that looks like Average R/W Block I/O size. Maybe it's called something else? Anyone?
Not sure if this is what you are after, but here goes. If you run NFS stat -d you get what the calls are and how many in each block size. By the way... you said that you have activated all special counters... can you send me any info on doing that? I am trying to measure average read and write latency for LUNs and when I try to build the view in the nmc I can see the counters that I want but it says that they are currently disabled.
Anyway... I have been looking into similar things lately and will post if I come across average block size.
Enable showing of diagnostic counters in DFM: dfm option set perfAdvisorShowDiagCounters=yes
Restart DFM and then create your custom views, charts, etc.
I think there should be a specific counter within DFM that would capture this as it's a pretty standard metric as far as I can tell. Using NFS stat -d does not provide me the average read/write I/O block size coming in from attached FC-host, so not sure that will work for all around analysis of SAN throughput as well as other NAS protocol's such as CIFS I/O request.