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Reliability

'Reliability' refers to the ability of the hardware to avoid failing. With the Itanium processor family, this ability is built directly into the processor. The prime example of the improved reliability of the processor is the built-in 'error correcting memory.' In a large system with megabytes of cache memory, a little thing like an alpha particle coming through the atmosphere can hit one of the memory circuits and change one of the bits. A change in the bit means that the value in the memory has also been altered.

An alpha particle strike is an example of a purely random error that occurs from environmental causes even though no "hard" failure has happened. It's not the result of a bad design or a component failure. However, the error correcting memory will fix the problem on the fly guarding against this effect.

This is because error correction introduces of 'parity check' that can tell whether a given bit should be 'on' or 'off', and even fix the piece of data.

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