Hello Eric,   First let's start with what firmware versions the existing arrays have and what it the new one.  If they are too far apart you won't be able to add the new to the grroup.  Your plan would work, as you can merge pools at any time w/o losing data. But often upgrading is the long term better option.  Presuming all the timeouts are set on the servers and VMs upgrades can be done live. It's important to be properly prepared so that if you had a controller failover during normal operation it would not interfere with VMs during production.   Doing the upgrade during a quieter IO period also helps keep the failover process short.  6210 has the latest and fastest processors as well.   Regards, Don  
Good afternoon All  I have a 2 unit SAN (PS6210  x 2) and I now have a new 3rd PS6210 - part of my problem is that the Firmware versions are 2 versions different so I can add the new one into the existing pool.  The 2 unit pool is almost full and it would mean quite a lot of disruption to upgrade the firmware straight away.   Is it possible for me to add the new unit as an independent pool, move some of my VMs to it then upgrade the 2 units and then add the new unit into the old pool?  Or would the adding destroy the data on the new pool?  Thanks  Eric
New PS6210 use first and add to pool later