You also might want to look at Support Solution emc311889 from PowerLink. This gives a bit more information about the way FAST VP looks at the hot and cold slices in the tiers.  glen
I know the FAST moves most busiest datas to Highest Tiers and Least busiest to Lower Tier. My question is what type of IO determines the HOT Chunks? Read or Write? What exactly FAST algorithm does?
I know the FAST moves most busiest datas to Highest Tiers and Least busiest to 
Lower Tier. My question is type of IO determines the HOT Chunks? Read or Write?