The reliability is provided by 4 concepts :
- The power supply can be share between several
boxes so that if one power supply fails, the box
doesn't go down.
- A battery can be
included to avoid using huge,
heavy and expensive UPS. Of course, batteries will
be shared between boxes to maximize uptime.
- A CompactFlash memory
card will replace a hard disk. No more mechanics,
this one isn't sensible to shocks.
- The filesystems will be mounted read-only whenever
possible. This way, in the case of a system crash,
risks of loosing data are fairly reduced, and system
comes up faster.