I have question in reference to upgrading the SAN-OS for our fabric. We currently run 2 MDS 9216's and 1 MDS 9120 with a SAN-OS of 2.1(1a), I have recently purchased another 3 MDS 9120?s to increase capacity and I would like to upgrade to SAN-OS 3.1(1) (Latest supported by our vendor, Hitachi Data Systems).
I have read through the documentation and think I have a good idea about how to do each switch upgrade. What I am unsure about is during the upgrade I will have a period of time, about 1 day, where some switches will be at a different SAN-OS than the others i.e. 2.1(1a) and 3.2(1). My question is ?Is it OK to run SAN-OS 2.1(1a) and SAN-OS 3.1(1) together in the same fabric??
My site consists of 1 VLAN and 2 sites redundantly connected via 2 paths.