Chemical DCS/SIS/MIS system clock synchronization (NTP server) construction
Chemical DCS/SIS/MIS system clock synchronization (NTP server) construction
At present, the time of network devices such as hosts and servers in the computer network is basically in a disordered state.
With the continuous emergence of computer network applications, the problem of computer time synchronization has become increasingly important.
Taking the Unix system as an example, the accuracy of time affects almost all file operations. If a machine's time is inaccurate, for example, if you create a file on a machine with an advanced slave time, use ls to check it. Subtracting the displayed file modification time from the current time will result in a negative value. This problem is a problem for network file servers. A disaster and the reliability of the document ceases to exist. To avoid native errors, the time can be obtained from the network, using the command rdate, so that the system clock can be synchronized with a public source. But once there is an error in this common time source, a domino effect will occur, and the time of all machines synchronized with it will be wrong.
Additionally, synchronization issues are even more important when it comes to security devices on the network. The logs generated by these devices must reflect accurate time. Especially when dealing with busy data, it's almost impossible to correlate logs from different sources if the times are out of sync. Security-related tools are useless once log files are not correlated. Out-of-sync networks mean businesses have to spend a lot of time tracking security incidents manually. Now let's take a look at how we can synchronize the network and make the security logs show accurate time.
The development of the Internet has made electronic money, online shopping, online securities, and financial transactions possible. Customers can perform the above activities while sitting at home using a personal computer. To ensure the normal conduct of these activities, there must be unified time. It cannot be imagined that the user remits a sum of money at 3 o'clock and the bank receives it at 2:50. The clock accuracy of a personal computer is very low, only 10-4 or 10-5, which may be off by more than ten seconds at the end of the day.
Many functions of many online teaching systems now use time records, such as Internet time records, homework submission time and exam time, etc. Usually the user data recorded by the online teaching system is based on the website server time. The author has previously experienced situations where the application server time is still at 23:55 and the database server has crossed 24:00, causing the entire ongoing batch processing or data archiving and other important processing to fail or not proceed at all. In fact, The application and database server times only differ by a few minutes. In order to avoid this situation, the system administrator should always pay attention to the server time. If the time gap is found to be large, it can be adjusted manually. However, manual adjustment by the system administrator is inaccurate and will be forgotten as the number of servers increases. Therefore, it is necessary to allow the system to automatically synchronize the time of multiple servers.
The solution to the above problem is to need a time management protocol that can adjust the clock jitter rate, establish an immediate moderation, adjust time changes, and use a group of trusted servers to provide accurate and stable time. This is the Network Time Protocol (NTP ). If your LAN can access the Internet, you don't need to install a special NTP server. You only need to install NTP client software to the public NTP server on the Internet to automatically correct the time. However, the time can be synchronized but it may not be accurate due to When the network is unstable and time synchronization fails, the best solution is to install your own NTP server hardware device in the network to synchronize and unify the time of each computer. The cost is not high, even if it is higher than that of a big data server. As a network engineer, you know better.
Summary:
As network scale and online applications continue to expand, the number of network equipment and servers continues to increase. When network administrators check the logs of many network devices, they often find that the time is inconsistent. Even if the time is set manually, there will be time errors caused by factors such as time zone or daylight saving time. After some Layer 2 switches are restarted, the clock will be restored to the initial value. Need to reset the time. For core network equipment and important application servers, they sometimes need to work together, so the accuracy and reliability of time is particularly important.
The configuration and use of the NTP service are very simple, and it takes up very little network data. NTP time servers are currently widely used in network security, online teaching, database backup and other fields. It's important for enterprises to take steps to synchronize network and device time, but ensuring that logs generated by security devices provide accurate time is even more important.