Where RTO is the planned target for restoring service, MTD is the hard limit beyond which damage — regulatory, contractual, financial, safety — becomes intolerable. Business impact analysis establishes MTD per process; continuity planning then designs recovery to land well inside it, since real recovery tends to overrun its plan.
Key points
Per-process settingThe same system serving two processes inherits the stricter of their MTDs; derive it from business consequence, not infrastructure convenience.
Margin under the limitRTO should sit comfortably below MTD — plans that target exactly the maximum have no room for the delays real incidents bring.
Important limitationMTD is an estimate of tolerance, not a measured threshold. It is set before the incident by analysis and judgment; the real point of failure may arrive sooner under conditions the BIA did not model.