Tony,  Upgrading from CX3-20 to CX4-120 will require a change in hardware (Storage Processor Enclosure) also. This is what provides higher processing power, 64-bit architecture, etc to the storage system. DAEs will remain in place. More details about the pre-sales considerations for upgrading to  EMC CLARiiON CX4 series storage systems can be found in Upgrading to EMC CLARiiON CX4 Series Storage Systems — Applied Technology whitepaper on Powerlink.  When you talk about adding flash drives to increase the amount of cache, I am assuming you are talking about FAST Cache. The potential benefits you might get when using FAST Cache will depend on the IO profile of your application. Please talk to your account team to explore this option. We will be coming out with more details as we get closer to GA.  Thanks!
Hi,  We have been running CX3-20 for around 3 years.  We find that FLARE 30 is released and it doesn't support CX3-20 SAN.  In this way, we are planning for upgrading CX3-20 to CX4 and update the FLARE OS as well.  We would like to know if we upgrade from CX3-20 to CX4, does it mean that it is only an upgrade of firmware OR have to replace the hardware ?  Moreover, we have another SAN running CX4-120 at remote site.  If we upgrade the FLARE OS to FLARE 30, would it be a good idea to add SSD so that we can increase the cache size ?  Thanks Tony 
Upgrade of CX3-20 SAN and FLARE 30 ....