Image: Headswap
There are 3 different types of Headswap with NetApp
Clustered ONTAP/ONTAP:
1) Non-Disruptive
ARL Headswap
2) Disruptive
Headswap
3) 7-Mode to cDOT
Headswap (aka 7MTT CFT or Copy Free Transition)*
*CFT is not
commonly called a headswap, but that’s pretty much what it is; removing shelves
and unassign-ing disks from a 7-Mode head (HA-pair), and assigning to a cDOT
head via the 7MTT tool.
I’ve previously covered CFT in these posts from July
2016.
The version of 7MTT was 2.3 back then, now its 3.1, but
the process hasn’t changed much. I think CFT is super simple, so - if you’re
still on 7-Mode, you can take a few hours outage for the HA-pair, and you want
to bring your shelves to cDOT (or even if you’ve purchased new shelves, you
could non-disruptively vol move from the old shelves post the CFT, and then
non-disruptively decommission the old shelves) - there’s no excuse for not using
it.
I’ve never written anything about CFT rollback, and
whilst everyone wants a 100% successful transition, it’s prudent to prepare for
a rollback scenario just in case. So in a future post I’ll write about CFT rollback and show it’s nothing to
be afraid of.
I have previously covered 7-Mode headswaps with the post:
In two future posts, I’ll post my notes for (similar to
the CFT “Step-by-Step High-Level Notes/Checklist”):
- Disruptive cDOT
Headswap
- Non-Disruptive
ARL Headswap
The Disruptive Headswap is of course the simpler and quicker
process, so if you have a limited change window, an available window of
downtime, or non-disruptive operations aren’t a requirement (perhaps it’s just
the DR site), then you might consider the Disruptive Headswap. If non-disruptive
is required, then Non-Disruptive ARL Headswap it is. One thing to remember with
Non-Disruptive ARL Headswap, is that you are a little exposed whilst the
procedure is in progress (since there’s no NVRAM mirroring between different
models of controller whilst in the interim state) - another Non-Disruptive
option is to add new nodes to the cluster, non-disruptively vol move volumes
across, and non-disruptively decommission the old.
Personally, I would say all 3 processes are relatively
straightforward, yet they all need to be treated with respect: prep thoroughly,
plan thoroughly, understand the process, understand the plan, and engage NetApp
Professional Services if there’s anything you’re uncomfortable with.
So, that’s the plan for the next 3 posts (time permitting
as always.)
3) Non-Disruptive
ARL Headswap: Step-by-Step
High-Level Notes/Checklist - which became the following 4 part series.
Performing a non-disruptive ARL (Aggregate Relocate) Headswap
for NetApp Clustered Data ONTAP - Step-by-Step Walkthrough Series:
Part
3 - Replace Node A with C, Relocating Aggregates to Node C and Retiring Node B
Part 4 - Replace Node B with D, Relocating Aggregates to Node D and Finish
Part 4 - Replace Node B with D, Relocating Aggregates to Node D and Finish
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