On a CX4-480, you can create FAST Cache in only two configurations using 200GB flash drives:  1. Use eight 200GB flash drives to create 800GB of FAST Cache.  2. Use four 200GB flash drives to create 400GB of FAST Cache (this requires FLARE 04.30.000.5.507 or later).  Details about all the possible configurations on various CX4 models can be found in the FAST Cache whitepaper on Powerlink.
All,  I think we're about to bite the bullet on FAST2, and we would like to implement FAST cache. We currently have 5 x 200GB EFD's.  What is everyone's recommendation on how much we should allocate for FAST Cache? I know..."it depends!"  Initially, we purchased the EFD's to be able to put our SQL data on them. I was going to configure it using 4+1. Since that SQL data is not 800GB, I was also thinking of housing the Index and tempDBs.  Currently, we have a MS CRM server that has well over 45 fibre spindles on the backend. Because the application is heavily customized, the application doesn't perform well even with that many spindles. The SQL data is on a 15 spindle configuration with 90% read, 10% write ratio.   My thoughts on the FAST Cache was to implement 2 x 200GB as a RAID10, and then use the rest for some other data LUN. Do you think I'll get better performance just using all the EFD's for FAST Cache, and possibly my money's worth? Pros and cons to "all fast cache" or "some fast cache and some for data?"  I see us implementing this technology in less than a month so your responses would be appreciated. You can also provide me any best practices that's available.  thanks in advanced!  j 
Implementing FAST CACHE on CX4-480