If you have enough free space,  I would move the PS6100 into its own pool,,  then move the volumes you need the R10 performance to that pool. 
All, We are looking to change the volume raid preference from Automatic to RAID specific.  We want to make sure that making this change doesn't have a huge impact on performance as data is being moved from slower array to performance array.  Any insight or thoughts on making this change would be much appreciated. Thanks!
Change Raid Volume Preference