Important formula for Mean Time Failures
MTTF - Mean Time To Failure
MTTF = 1 / failure rate = Total #hours of operation / Total #units
MTTF is an averaged value. In reality failure rate changes over time
because it may depend on age of component.
Failure rate = 1 / MTTF (assuming average value over time)
MTTR - Mean Time to Recovery / Repair
MTTR = Total #hours for maintenance / Total #repairs
MTTD - Mean Time to Diagnose
MTBF - Mean Time Between Failures
MTBF = MTTD + MTTR + MTTF
MTTF - Serial assembly
MTTF of system = 1 / SUM (1/MTTFi) for all components i
Failure rate of system = SUM(1/MTTFi) for all components i
MTTF - Parallel assembly
MTTF of system = SUM(MTTFi) for all components i
Availability = Time system is UP and accessible / Total time observed
Availability = MTTF / (MTTD* + MTTR + MTTF)
or
Availability = MTTF / MTBF
All the messages below are just forwarded messages if some one feels hurt about it please add your comments we will remove the post. Host/author is not responsible for these posts.
