We use multiple uplinks using bgp4 path routing, over cisco routers. If one link goes down, bgp automatically routes traffic via standby links.

All our hardware is on UPS filtered battery backup power, and all our web servers have built in dual redundant hot swapable power supplies. If a power supply fails the server automatically uses the standby power supply without interruption. The failed unit can then be replaced without powering down the system.

All our web servers use RAID 5 and mirroring technology, this allows the system to continue without interruption should a live hard disk fail.

The web servers have dual hard disk drive systems:

The first system is RAID 5. This means your data is written across at least 3 drives with enough extra checksum information so that if a drive fails the system can continue running without interruption from the information on the remaining drives without loss of data. All RAID 5 drives are hot swapable, meaning that we don't need to power the system down to replace disk drives. Even more impressive, the RAID 5 system has its own private standby drive onto which it automatically rebuilds itself from the remaining drives in the event of a failure, all without human intervention or down time. The system literally heals itself.

The second disk subsystem acts a mirror to the RAID 5 system, so an online disk copy of your data is always available ready to continue should the entire RAID 5 system fail, without the lengthy delays experienced when having to restore from backup tapes.

Every web server is monitored 24/7 for performance and a human operator is automatically contacted to investigate and quickly respond to any system lag or down time.

As a final precaution we backup to tape every night.

All these features add up to serious reliability and give us the confidence to offer you our reliability guarantee.