I'm a little uncertain about what's possible with VM reservations and I'd like to know what's possible and (if applicable) automatic about reservations. I understand that there is an exchange process and that if the exchanged reservation increases in price then there's no penalty but I'm trying to understand whether the following scenarios would require an exchange and if they'd be permitted:
Server 1a is a B-series B16ms and its replacement Server 1b is a B32ms
Server 2a is a B-series B16ms and its replacement Server 2b is a B8ms
Server 3a is a B-series B16ms and its replacement Server 3b is F32s_v2
In the first 2 scenarios, I've read (somewhere) that Azure will use reservations that match the same instance series and will scale the discount up-or-down accordingly. Is that true or would I need to run through the exchange process?
In the final scenario, the instance series is changing. I appreciate that this is still a VM reservation so my question is does this count for the purposes of an exchange or do you need to stay on the same series? The documentation I've read states that an exchange is possible if they are similar reservations but I'm unclear on what is 'similar'.
You need to stay with the same series, for example, a reservation purchased for ES series VMs don't apply to E series VMs, and vice-versa, in your examples above it should work, but the 3a reservation will need to be changed.