I have a Storage pool that is composed of 15 600GB SAS drives and 4 3TB NL-SAS drives.  Tiering is set to automatic.  This pool contains a mix of LUNs which include many for VMware (VMFS LUNs) as well as several for Exchange databases.  I'm starting to experience delays in the storage system (increased latency according to VMware) and evening backups are starting to slow down (mostly noticed in Exchange DB backups).  I just purchased 15 more 600GB drives along with a DAE.  Which would help with the overall performance?  Adding the new drives (using the recommended 4+1 RAID grouping) into the existing storage pool to increase overall drive count to 34 and distribute the load across more drives.  Or just building a new storage pool on the new drive and moving some LUNs over to it?  This is part of a VNX 5500 running FLARE 5.32.  So expanding an existing pool should re-balance the pool across all drives.

Thanks!

Joe P.