Troubleshooting Storage Performance in vSphere Links from Vmware Blog

http://blogs.vmware.com/vsphere/2012/05/troubleshooting-storage-performance-in-vsphere-part-1-the-basics-.html
http://blogs.vmware.com/vsphere/2012/06/troubleshooting-storage-performance-in-vsphere-part-2.html
http://blogs.vmware.com/vsphere/2012/06/troubleshooting-storage-performance-in-vsphere-part-3-ssd-performance.html
http://blogs.vmware.com/vsphere/2012/07/troubleshooting-storage-performance-in-vsphere-part-5-storage-queues.html