Scrum is useless for that team, you are right. You can't do scrum if more than 1/2 your work is ad hoc support tickets. When I ran SRE at Netflix, our general

Scrum is useless for that team, you are right. You can't do scrum if more than 1/2 your work is ad hoc support tickets. When I ran SRE at Netflix, our general trick was one person is on support for the week. They were the primary on-call, they handled any emergency support. Everyone else was primarily building, or at least doing longer-term follow up work from support tickets. In major emergencies of course everyone would drop what they were doing and help, or if a support ticket came through for a tool someone else built, it was fine to ask them for help. But at least the mindset was "jedberg is on call this week, so don't expect him to be building anything this week". We also had good management support so that when we went to review our quarterly goals, and 75% of them were red, they trusted us to know that it was because we had a lot of support load that month. Everyone who depended on our tools knew that they would be ready when they are ready.