Longest time a business function can be unavailable before causing unacceptable damage.
Maximum Tolerable Downtime (MTD) is the longest period a business function can be unavailable before causing unacceptable harm—financial losses, regulatory breach, reputational damage, or threats to survival. MTD defines the outer limit for recovery; RTO must be shorter than MTD. Understanding MTD helps calibrate recovery investments—functions with short MTD need robust, rapid recovery capabilities; those with longer MTD can accept simpler approaches.
Why It Matters
The DSC Perspective:
MTD defines how long you have. If your critical system has 24-hour MTD but 48-hour recovery capability, you have a problem. Ensure recovery capabilities align with MTD requirements.