Storage - When you pool storage together into a Storage Area Network (SAN) or a Network Attached Storage (NAS) device.
I/O - When you aggregate I/O devices into a single unit, such as an Ethernet switch module on the back of a blade server chassis.
Some people consider blade servers as a means of compute server consolidation, but unless you are implementing virtualization on the blades, you will still have the same number of physical servers. In fact, blade servers represent I/O consolidation.
This was first published in June 2007