The dual-server hot standby is for server failures. Server failures can be caused by various reasons, such as equipment failure, operating system failure, software system failure, etc. Generally speaking, it can take 10 minutes, hours, or even days to restore the server to normal with technicians on site. In practice, unless the server is simply restarted (which may still be a problem), it often takes more than a few hours. And if the technician is not on site, the time to resume service is longer.
For some important systems, it is difficult for users to endure such a long service interruption. Therefore, it is necessary to avoid long-term service interruption and ensure long-term and reliable service of the system through dual-machine hot standby.
The correct way to decide whether to use dual-machine hot standby is to analyze the importance of the system and the tolerance for service interruption to decide whether to use dual-machine hot standby. That is, how long your users can tolerate restoring service, and how much impact it will have if it does not resume.
When considering dual-machine hot standby, it should be noted that there will be a switching process for dual-machine hot standby in a general sense, which may take about a minute. During the switchover, the service may be interrupted for a short time. However, when the switchover is complete, the service will resume normally. Therefore, the dual-machine hot standby is not seamless and uninterrupted, but it can ensure that normal service can be quickly restored in the event of a system failure, and the business will not be affected. If there is no dual-machine hot standby, there may be a service interruption for several hours in the event of a server failure, which may have a serious impact on the business.
Another point to emphasize is that the failure of a server is different from the failure of a switch or storage device, and its concept is much higher. The reason is that servers are much more complex devices than switches and storage devices, and they are also complex systems that include hardware, operating systems, and application software systems. Not only can equipment failures cause service interruptions, but software issues can also cause servers to not work properly.
It should also be noted that some other protective measures such as disk array (RAID) and data backup are very important, but they cannot replace the role of dual-server hot standby. See the related article: Relationship between dual-server hot standby and data backup/RAID.
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Posted on 2/16/2015 9:10:34 PM
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