vCMP Upgrade : do I need to change the Guests' "Initial Image" to match the new iso before Deploying the guest again ?

Hello there,

we are planning to upgrade our vCMP Hosts and all of the hosted Guests to version 11.4. (Platform BIG-IP i5800)

Yesterday I succesfully upgraded the Host and its Guests in our 'test' enviromnent, but before I schedule the upgrade in production I really want to know if it is recommended to change the "Initial Image" setting on vCMP Guests to match the new ISO before deploying them back online.

This has bothered me quite a lot yesterday, and I found a couple different opinions on this

• https://techdocs.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/vcmp-viprion-configuration-11-2-1/7.html This is for version 11.x and it states the following:

Important: You may choose to not change the ISO image in cases where the upgrade is temporary (for example you might be trying out a specific software update to see if it addresses an issue, and after evaluating that update, you may well choose to go back to the prior software version). As long as the ISO image version of the other cluster members matches the version currently specified at the time you perform the hot swap, the guest will re-create successfully.

• https://devcentral.f5.com/s/question/0D51T00006i7fS4/steps-to-upgrade-a-vcmp-host In this 2yo post I could read mr. Jerry Leed's answer stating that

This is as you have stated above, all of it. In fact, it is recommended that when code upgrades that you DO change the initial software version and the initial hotfix version to the version running now. This is the setting that tells the vCMP subsystem what images to build a guest as when it builds teh guest again (should it need to). This is especially important on Viprion Chassis where the guest may beed to span to a new blade due to a blade failure. Otherwise the guest gets built with the incorrect software version and when the configuration is sent to the new guest, it may not load properly. (read probably not at all into that last bit)

I would just get some kind of definitive yes/no before I schedule production upgrade so that everything runs at its best.

In the end I did not change the ISO on the Guests I upgraded yesterday, and I can see they run nice ; but I'm also willing to delete the old ISO from the HD and I don't really know if that could cause a problem with a successive re-deployment of the Guests.