MTTD
An SRE incident metric, complementary to MTTR in EDI monitoring.
Definition
MTTD measures detection latency: the time elapsed between an incident occurring (for example a stalled EDI flow) and alerts surfacing it. It precedes MTTR in the incident lifecycle; a high MTTD reveals blind spots in observability and alerting. It is also distinct from MTTA (mean time to acknowledge).
Origin
A standard incident-management and reliability (SRE) metric, described notably in the Google SRE Book (O'Reilly).
Example in context
An AS2 connector fails at 02:00 but the alert only fires at 02:25 — MTTD = 25 minutes.
Related terms
- SLA EDI — service commitments often including MTTR.
- Error budget — SRE error budget.