Hello,
Today, I would like to share with you this topic which present a classic analysis between MTBF & MTTR.
Mean Time Between Failures (MTBF)
It refers to the average time between two faults of a repairable system, that is, the ratio of the cumulative operating time of the system to the number of faults. This indicator is used to measure the stability of the product.
There is an inverse relationship between MTBF and failure rate λ: MTBF = 1 / λ. For example: 1000 devices are running on the Internet, and there are 20 failures in one year. The annual failure rate of the device is λ = 20/1000 = 2%. At this time, MTBF = cumulative operating time / fault times = 1000/20 = 50 year.
Mean Time To Repair (MTTR )
The ratio of the total time for repair repairs to the total number of faults of the products repaired at this level at any given maintenance level. This indicator is used to measure the maintainability of the product.
For example, if the total time of service interruption caused by 20 failures of a certain device is 40 hours, MTTR = 40/20 = 2 hours.
Availability (A)
Capabilities available when needed. That is, the ratio of the product's normal operating time to the total operating time (including failure time): A = MTBF / (MTBF + MTTR). Usually also called availability or availability.
For example, if MTBF of a certain device = 50 years = 438000 hours and MTTR = 2 hours, the availability of the device A = MTBF / (MTBF + MTTR) = 438000 / (438000 + 2) = 0.9999954.
Failure rate
The proportion of products that can work to a certain point of time in the subsequent extremely short continuous unit time is used to measure reliability. The unit is Fit (Failures in Time): 1 Fit = / hour, That is, the probability of product failure within 1 hour is that the smaller the value of this indicator, the higher the reliability of the system.
Note :
The availability formula A = MTBF / (MTBF + MTTR) is the basis for us to evaluate availability and improve services. From the formula, we can see that improving availability can start from two aspects, increasing MTBF and reducing MTTR.
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