Availability

MTBF, MTTR, a spare on the shelf or a second unit: see which one really buys uptime.

Try it: what buys availability

MTBF20,000 h

About 2.3 years between failures.

MTTR (order, deliver, fit, recommission)48 h

Without a spare, the repair waits for the part.

Cost of an hour of lost production5.0 k€/h

One drive: every failure costs the whole repair time. Try halving MTTR, then doubling MTBF instead: the gain is the same.

A = MTBF / (MTBF + MTTR) ; N+1: A = 1 − (1 − A₁)²