CISSP考试指南笔记：7.5 网络和资源可用性

Another key component of security operations is planning for and dealing with the inevitable failures of the component parts of our information systems.

The network needs to be properly maintained to make sure the network and its resources will always be available when they’re needed.

Device backup and other availability solutions are chosen to balance the value of having information available against the cost of keeping that information available:

• Redundant hardware ready for “hot swapping” keeps information highly available by having multiple copies of information (mirroring) or enough extra information available to reconstruct information in case of partial loss (parity, error correction).

• Fault-tolerant technologies keep information available against not only individual storage device faults but even against whole system failures.

• Service level agreements (SLAs) help service providers, whether they are an internal IT operation or an outsourcer, decide what type of availability technology is appropriate.

• Solid operational procedures are also required to maintain availability.

Mean Time Between Failures

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Mean time between failures (MTBF) is a measure of how long we expect a piece of equipment to operate reliably.

MTBF implies that the device or component is repairable. If it isn’t, then we use the term mean time to failure (MTTF).

Mean Time to Repair

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Mean time to repair (MTTR) is the expected amount of time it will take to get a device fixed and back into production after its failure.

 

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