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Availability of Cyber Security

Availability is expressed as a percentage of uptime over various time periods, with different applications requiring different levels. High availability, such as 99.999%, may necessitate triple redundancy and significant investment. Additionally, availability can be calculated using mean time between failure (MTBF) and mean time to repair (MTTR).

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10 views4 pages

Availability of Cyber Security

Availability is expressed as a percentage of uptime over various time periods, with different applications requiring different levels. High availability, such as 99.999%, may necessitate triple redundancy and significant investment. Additionally, availability can be calculated using mean time between failure (MTBF) and mean time to repair (MTTR).

Uploaded by

faiz.khan
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Availability

• Availability can be expressed as a percent


uptime per year, month, week, day, or hour,
compared to the total time in that period
– For example:
• 24/7 operation
• Network is up for 165 hours in the 168-hour week
• Availability is 98.21%
• Different applications may require different
levels
• Some enterprises may want 99.999% or
“Five Nines” availability
Availability
Downtime in Minutes
Per Hour Per Day Per Week Per Year

99.999% .0006 .01 .10 5

99.98% .012 .29 2 105


99.95% .03 .72 5 263

99.90% .06 1.44 10 526

99.70% .18 4.32 30 1577


99.999% Availability May Require
Triple Redundancy

ISP 1 ISP 2 ISP 3

Enterprise

• Can the customer afford this?


Availability
• Availability can also be expressed as a
mean time between failure (MTBF) and
mean time to repair (MTTR)
• Availability = MTBF/(MTBF + MTTR)
– For example:
• The network should not fail more than once every 4,000
hours (166 days) and it should be fixed within one hour
• 4,000/4,001 = 99.98% availability

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