Backup before Update

[FlyingHacker]

I am putting together a backup TrueNAS Core server. The production server is running 13.0-U1. Should I install U1 on the backup first and get it going just like the production server, and then upgrade to U2. Or is it best to go ahead with U2 on the backup server, get everything backed up and working, and then upgrade production to U2 ?

Thoughts?

Thanks in advance.