hello emcmagic,  Is there a document that details on how initially FAST VP variables should be determined? SPA views can be used to profile application I/O before a FAST policy is created. The statistics generated can then be used as a guide for configuring an appropriate FAST VP policy for the application. You can use the SPA Snapshot Hit/Miss Distribution view to determine applicable workloads and to target Symmetrix tiers for FAST VP. For example, the below pasted image shows a significant amount of average read miss activity for a storage group. In this case, the group may be better placed partly on the EFD tier and the FAST policy can be configured accordingly. [IMAGE]  [IMAGE]  You can use the SPA storage group Diagnostic view to produce graphs of application I/O spread. For example, the following Host IOs/sec graph of the storage group shows that there is a skew in the workload for the devices in this storage group. Approximately 15% of the devices are being hit harder with I/O than the others. The devices related to this 15% of the storage group may be suitable candidates for up-tiering from FC to EFD.  [IMAGE] [IMAGE]  what tool can I use to find out skew number? Tier Advisor is a modeling tool that EMC uses, to estimate the performance and cost of mixing different types of disk drive technology within EMC storage arrays. It helps you determine whether to add, upgrade, or replace existing storage to achieve optimal performance and cost effectiveness in your storage environment.  Remember:FAST VP is most effective in an environment where the workload tends to be skewed and the skew patterns are dynamic. FAST VP is not beneficial if the workload is not skewed or if the I/O workload is static, since workload skews if static, can be addressed using manual methods such as VLUN Migration.  Sean's blog makes a very nice point about changing the PRC for the EFD and SATA tiers.  regards.
I have 3 policies as following. FP_HIGH has 3 tiers defined, the others 2 policies only have 2 tiers. In addition, for FP_HIGH policy there is 10% sg as up limit to use EFD tier. For FP_LOW   there are 30% to use FC tier and 100% to use SATA tier. For FP_MEDIUM, there are 90% to use FC and 100% to use SATA tier.  My questions are: At beginning, how do we determine the number of tiers should be defined for each policy and what percentage of sg should be able to use what tiers? I know FAST VP can perform performance analysis on workloads, since we don't know how the performance will look like at beginning, does that mean we will have to let the  array to  run for a while, and collect performance metrics first before we can make our mind on these parameters?  Thank you!  # symfast -sid 123 list -fp --------------------------------------------- Policy Name                      Tiers Assocs -------------------------------- ----- ------ FP_HIGH                              3     11 FP_LOW                               2      0 FP_MEDIUM                         2     61  # symfast -sid 123 list  -fp_name FP_HIGH Policy Name           : FP_HIGH Tiers(3)     {      ------------------------------------------------------------------                                             Max      SG       Target     Tier Name                        Type  Percent Tech  Protection     -------------------------------- ---- -------- ----- -------------     EFD_RAID-5_3plus1_VP_1           VP         10 EFD   RAID-5(3+1)     FC_RAID-1_VP_1                           VP        100 FC    RAID-1     SATA_RAID-6_14plus2_VP_1       VP        100 SATA  RAID-6(14+2)     }
how to determine how many and what tiers in each policy and what sg % for each 
tier?