We are looking at upgrading our firmware on our CX500, brocade switches and QLogic HBAs. Currently, our luns are mixed between SPA and SPB. HBAs will not be an issue, but obviously, the SPs and switches will be patched 1 at a time. Without planning, this should force a trespass on the half the luns. How will ESX and the guest VMs respond. Each LUN currently has four paths and they are set up MRU.
We are having an engagement with EMC for this, but I would really like to hear from VMware admins how this has gone in the past.