Dual-machine Hot Standby implementation mode-based on shared storage and pure software

The dual-host hot storage provides two implementation modes: one is based on shared storage devices, and the other is based on non-shared storage devices, which are generally called pure software.

Storage-sharing-based hot standby is the most standard solution for hot standby.

In this way, two or more servers are used (for more information, see the similarities and differences between dual-host and cluster servers) to use shared storage devices (disk array cabinets or Storage Area Network SAN ). The two servers can adopt different methods, such as mutual backup, master-slave, and parallel. In the course of work, the two servers will provide external services with a virtual IP address, and send service requests to one of the servers according to their work methods. At the same time, the server uses a heartbeat line (usually using a private network) to detect the working status of another server. When one server fails, the other server makes a judgment based on heartbeat detection, switches over and takes over the service. For users, this process is fully automated and completed in a short time, so as not to affect the business. Because shared storage devices are used, the two servers use the same data, which is managed by the dual-host or cluster software.

(For Typical Dual-host hot standby products, see landercluster cluster software)

The software-only method is to copy the data to another server in real time through the dual-host software that supports mirroring, so that the same data exists on each of the two servers, if one server fails, you can switch to another server in time.

For in-depth analysis of this method, see: in-depth analysis of Dual-machine Hot Standby solution in software-only mode

The software-only method also has another situation, that is, the server only provides application services and does not save data (for example, only some calculations are performed and used as application servers ). In this case, you do not need to use shared storage devices. Instead, you can directly use dual-host or cluster software. However, this situation has nothing to do with the image, but it is a small change in the standard hot standby mode.