Zusammenfassung der Ressource
Hst 4.2 Availabilty percentages and intervals
- Availability
Levels - SLA
- Uptime in period of
time in month/year
- 99,8%
- 99,9% (3 nines)
- 99,99% (4-nines)
- carrier grade availability =
extremely high availability
- 99,999% (5-nines)
- MTBF = Meam Time
Between Failures
- average time
that passes
between failures
- expressed in hours, how many
hours will the component or
service work without failure
- MTBF = (see boek page 55 for example.)
- MTTR = Mean
Time To Repair
- which is time to take to
recover from a failure
- manual actions
- components
repair
- notifications of the fault
- processing alarm
- find root cause of error
- looking up repair information
- spare componenets from storage
- technician to datacenter for repair
- restarting and testing the components
- components
replace
- Availability =
- calculation example see boek page 56-57
- serial availability
- when a failure of any part in a system
cause a failure of the system as a whole
- system with serial
components
- to increase availability
- Two systems in parrallel