Redundancy – Critical systems must be designed to continue functioning in the event of hardware or other critical component failure. Critical systems such as Email Servers, Data Servers, and other Critical Servers require redundant hardware. Another important approach to consider is On-Site and Off-Site Backup, Data Replication, and Fail-Over Systems
Sample Redundant Server and Infrastructure Design
There are many components in a network that can be make redundant.
Some examples are listed below:
- Servers - A backup server can act as a secondary system in the event of a primary server failure. Fail-over can be automatic or manual.
- Disks - Mirroring or RAID configurations provide important disk redundancy.
- Server Power Supplies - Most servers are powered by dual supplies, if one fails, the other will automatically take over.
- Network Cards - Servers also include dual network cards.
- Dual Internet Providers with automatic fail-over from Primary to secondary or used in load balancing mode.
- Dual Routers with fail-over link between them.
- AC Power -Dual Uninterruptible Power Supplies (UPS) in conjunction with servers using dual power supplies are used to provide power if primary power fails.