[peterwwillis]

If you're building a system from scratch, keep in mind that this way of designing your service may not be flexible enough. You don't want just service level objectives, agreements and indicators, you want customer level.

Your service may end up providing for multiple customers with different requirements. Maybe 1% of your customers will end up using 99% of your resources, creating uncomfortable situations that affect the other 99% of customers. To get away from this you have to start spinning off multiple identical services just for groups of customers, which is really annoying to maintain. You may find you need to add hard resource limits to control customer behavior, which is hard to add after the fact.

Instead, if you design your new system from scratch with customer-specific isolation and service levels, you can run one giant service and still prevent customer-specific load from hampering the rest of the service. You can also just run duplicate services at different levels of availability based on customer requirements, but that's not going to work forever.

As an aside, I'm looking forward to reading ITIL 2019 to see what new processes they've adopted. I think everyone who's getting into SRE stuff should have a solid foundation on the basics of IT Operations management first.