[ Thanks to Paul
Shread for this link. ]
“The ideal for cloud storage is to be self-managed,
self-balanced and self-replicated, with regular data checksums to
account for the undetectable or mis-corrected error rates of
various storage technologies. Cloud storage depends on being able
have multiples copies of files managed and checksummed and verified
regularly, distributed across the storage cloud for safekeeping.“It’s a great idea, but it faces more than a few challenges,
such as reliability, security, data integrity, power, and
replication time and costs. But one of the biggest issues is simply
that hardware is going to break. There are two ways disk and tape
drives break:* Hitting the hard error rate of the media, which is expressed
in average number of bits before an error occurs
* Hitting the Annualized Failure Rate (AFR) of a device based on
the number of hours used“The most common type of failure is known as the vendor’s bit
error rate. The bit error rate is the expected failures per number
of bits moved. The following is generally what is published by
vendors:”