Storage IOPS is probably the most overlooked area in consolidated environments. DBAs should look at average and peak IOPS for each database or application to be consolidated as part of the consolidation planning exercise.
Use AWR reports to collect the following I/O metrics.
IOPS = “physical reads total I/O requests” + “physical writes total I/O requests”
MBytes/s = “physical reads total bytes” + “physical writes total bytes”
These metrics will aid in determining storage throughput needed to support the application. Aggregate the IOPS or MBytes/s for all nodes if the existing application is running on RAC
If we are able to get this information on let’s say top 10 critical databases and after reviewing the stats if they are not utilizing more power in terms of cpu, ram and storage then we can reconfigure / consolidate them and do some cost savings there.
You can configure and use SLOB – The Silly Little Oracle Benchmark
This tool can help measure storage performance in terms of IOPS
Reference
http://kevinclosson.net/2012/02/06/introducing-slob-the-silly-little-oracle-benchmark/
http://www.pythian.com/blog/my-slob-io-testing-index/
http://pardydba.wordpress.com/2013/02/15/collection-of-links-tips-and-tools-for-running-slob/
http://www.cloudbyte.com/docs/Whitepaper_CloudByte_Measuring-Storage-Performance.pdf
Prashant Atri Blog 