HP switches - how to copy configuration between different device models

A couple of days ago I did a planned software upgrade of an HP5406zl.

Since the installed firmware version was quite old it was not possible to update directly to the latest release, an upgrade path must be followed:

This is how it went:

A faulty flash killed the switch so it was replaced with a spare part, an HP5412zl, the same switch but with twelve modules instead of six.

Problem

Copy the old config to the new switch caused a "wrong file" error message.

How to fix

The switch configuration file starts with a definition of the model.

This is on a 5406zl:

; J8697A Configuration Editor; Created on release #K.15.14.0007
; Ver #05:18.7f.ff.3f.ef:4d

And this on a 5412zl:

; J8698A Configuration Editor; Created on release #K.15.10.0009

; Ver #03:03.1f.ef:f0

Just replace those two lines with the correct model and the configuration will be loaded correctly.

Lesson learned

Always backup the configuration before any change or software upgrade. This single step, skipped by many network engineers, saved me so many times.

Be ready for the worse. My company has spare parts for almost all the devices installed to customers, this HP5412zl has enough modules and features to replace most switches we install so it's good to know it's there just in case.

How it went

HP replaced the switch (lifetime warranty for the FTW!), I did the upgrade in a test environment, copied the configuration and put it back where it belongs.