CRITICAL SYSTEMS AND FUNCTIONS
MTD (Maximum Tolerable Downtime) is the longest period of a business outage without causing permanent business failure. Each organization will have its own MTD.
RTO (Recovery Time Objective): This is the expected time to get a system back online and functional. If the RTO exceeds the MTD, plan to move to an alternate site.
RPO (Recovery Point Objective): This measures how much data the company will lose in a given time. If the RPO is 4 hours, the backup must run every 4 hours; if the RPO is 12 hours, a backup must run every 12 hours.
KPI (Key Performance Indicators): This measures the reliability of an asset such as a server.
1. MTTF (Mean Time to Failure): This is normally an estimate of a product's expected lifetime, estimated in thousands of hours.
2. MTBF (Mean Time Between Failures): This is the rating of a component/device that predicts the time between failures. It can be listed in tens of thousands or thousands of hours.
3. MTTR (Mean Time to Repair): This is the actual time it takes to get a system back online. People often confuse this with RTO, which is the expected time, not the actual time to repair. This can also be called "replace" or "recover".