MAD, MTD, RTO

I am looking for a clear understanding for the following definitions and the difference between them.

MAD Maximum Allowable Downtime
MTD Maximum Tolerable Downtime
RTO Recovery Time Objective

Answer:
MAD and MTD are similar concepts, because they are related with the maximum time that a process, service, system, etc. can be inoperative or unavailable. Similar concepts also are MAO (Maximum Acceptable Outage) and MTPD (Maximum Tolerable Period of Disruption) which are used by ISO 22301 (official definition for both in accordance with ISO 22301: “time it would take for adverse impacts, which might arise as a result of not providing a product/service or performing an activity, to become unacceptable”).

Regarding the RTO, in accordance with ISO 22301: “period of time following an incident within which product or service must be resumed, or activity must be resumed, or resources must be recovered”.

So, in a disaster scenario, time to recover a part of the business (services, activities, etc) is related to the RTO, and time to recover 100 % the entire business is related to the MAD and MTD (or MAO, MTPD).

Maybe this article about the BIA can be interesting for you “How to implement business impact analysis (BIA) according to ISO 22301” : https://advisera.com/27001academy/knowledgebase/how-to-implement-business-impact-analysis-bia-according-to-iso-22301/

And also this article "What is the difference between Recovery Time Objective (RTO) and Recovery Point Objective (RPO)" : https://advisera.com/27001academy/knowledgebase/what-is-the-difference-between-recovery-time-objective-rto-and-recovery-point-objective-rpo/