| 3 | 3 | High availability refers to a system and associated service implementation that is continuously operational for a long period of time. Whole-system replication is a conventional way to increase system availability -- once a primary machine fails, the running applications are migrated and resumed on backup machine(s). However, there are several limitations that make this method unattractive for deployment: it needs specialized hardware and software, which are usually expensive. Additionally, such a system may also require complex customized configurations, which are difficult to manage and maintain. |
