【 Weak current College 】 standby service reorganized necessity

Hot standby service is a lot of enterprise is in use or is starting to grow old with technology. As the technology development we have a certain experience. Long time of use, which is enhanced by our understanding of the technology. Hot standby service concept includes two broad and narrow.

Broadly speaking, it is important, use two servers, each backup to perform the same service. When a server fails, you can from another server, bears the service task, which does not require human intervention, automatically ensure that the system can continue to provide services.

Hot standby generally require shared storage devices. But in some cases you can also use two separate server.

Implement hot standby service needs through professional cluster software or computer software.

In a narrow sense, hot standby service especially based on active/standby mode Server hot. Server data includes database data simultaneously to two or more servers, or use a shared storage device. At the same time, only one server running. When running a server fails to start, another backup server software consultation survey (typically by heartbeat Diagnostics) to activate the standby machine, ensure that application in a short time to completely back to normal use.

Why do hot standby? hot standby service is the server's fault.

Server failure could be caused by a variety of reasons, such as equipment failure or operating system failure, software, system failures, and so on. Generally speaking, the technical personnel at the scene, the recovery server normally might need 10 minutes, hours or even days. From practical experience, unless you simply restart server (with possible risks still exist), or they often take several hours. But if the technician is not in the scene, the recovery service time is longer.

But for some important system, the user is very difficult to put up with such a long interruption in services. Therefore, you need to pass the hot standby service, to avoid prolonged interruption in services, ensure the system is long-term, reliable service.

Decide whether to use standby service, the correct approach is to examine the importance of the system and the degree of service interruption, to determine whether to use a hot standby. That is, your users can tolerate long recovery service, if the service cannot be restored will cause many influences.

In considering the hot standby service, you need to note that general sense of the hot standby will have a switch, the switch process may be a minute or so. During the switching, service is possible short outage. However, when the switch is completed, the service will resume normal. Therefore, the hot standby service is seamless, uninterrupted, but it can guarantee that in the event of a system failure, the ability to quickly restore normal service, the business will not be affected. But if you do not have a hot standby, in the event of a server failure, there may be several hours of service interruption, the business impact can be very serious.

Another point that needs to be stressed that the server failure and switches, storage devices, the concept is much higher. Because the server is compared to the switch, storage devices, much more complex equipment, but also includes hardware, including operating system, application software system of complex systems. Not only the equipment failure could cause service disruption, and software issues may also cause server not working properly.

It should also be noted that some other protective measures such as a disk array (RAID), data backup is very important, but it cannot replace the role of standby service.