I try to explain it a lot:
our Customer has 2 rooms & in each room he has:
- one VPLEX engine & one VNX5700
We have sale the following configuration :
- one NEW VPLEX engine (should replace the old one) & one VNX5800 (for replacing the VNX5700)
Our Customer cannot shutdown his servers during the swap, so we need to find a solution to migrate the actual infrastructure with the new one without downtime.
The problem is: how to change the VPLEX engines without downtime ?
I think the best way is Host side LVM mirror.
If you add new VPLEX into existing congiruation to create a Metro and then cross connect host to new VPLEX cluster, we will still get many troubles in removing old VPLEX cluster out.
And PPME doesn't work well for such migration neither.
You can swap VPLEX hardware without downtime, a single engine will be replaced at a time. If redundancy is setup correctly you can run the system using other engines. The new engine will assume the wwpns of old engine. Swaps are non disruptive and does not require host side migrations in dual or quad engine system.
In a single engine system you might need to at other alternatives as host side mirroring as it requires downtime.