Hello,  Either will work.   Generally, speaking mixing small 10K/15K members with very large 7.2K RPM members can reduce the effectiveness of the faster drives.  Since more of the data will on the larger member.  This is especially true if they are running the same RAID type.     I would start with them in their own pools.  Later on, you can merge the two pools quite easily.  Going the other way is more involved.  Since you have to remove a member, which leaves the data in the original pool.  Then you can move volumes to the new pool.  Also please review Dell TR1091.  It covers how to configure ESXi w/EQL storage.  en.community.dell.com/.../download One small change that hasn't been added yet to that TR is the NOOP_TIMEOUT value.  The document shows you how to change the LOGIN_TIMEOUT value to 60.  In that same menu is the NOOP_TIMEOUT, that gets set to 30 seconds.  Lastly make sure the VMs themselves are configured with their Disk TimeOut values set to 60 seconds.  WIth the EQL Firmware downloads is a PDF titled "iSCSI initiator and OS considerations Optimizing Your SAN environment for High Availability"   That covers how to make the changes needed.  Regards,   Don 
Hello,  We recently received a new Equallogic SAN, and I am trying to decide how to implement. Our first unit (currently only member in a pool) is a PS4100 with 24x600GB 10K SAS. The new unit is a PS4210 with 12x4TB 7.2K NL SAS.  Should I leave the units in separate pools in the same group, and carve out new LUNS? Should I add the PS4210 into the existing pool, and utilize storage tiering? I'm a bit unsure about how the storage tiering will work, I've read quite a bit that when mixing disk types, storage tiering will balance on capacity, and most of the IO load will hit the higher capacity SAN.  Any input is appreciated. The storage is used for VMFS datastores with vSphere 5.5 cluster. Running EQL firmware 8.1.0 on both units. 
Best Practice inquiry: storage tiering with differing disk types