Does the server have to be SSD hard drives? What are the advantages and disadvantages of using SSD?

Many customers don't know how to choose a server hard drive. Is it necessary to use an ssd hard drive?
This problem mainly depends on the application. Many servers do not need to use SSD.
The biggest advantage of SSD is high IO performance, that is, it loads programs and reads and writes data quickly.
But for the server, it is powered on 24 hours a day, running a fixed service all the time, and does not restart or shut down once a few months or even a year, and it hardly needs to load programs.
In terms of reading and writing data, it depends on the specific application. If it is a data server or mail server, which needs to read and write hard disk data frequently, SSD has advantages. But there are also many servers that rarely need to read and write hard disk data, such as domain controllers, DNS/DHCP servers, static web servers with a small amount of files, and so on.
Although some servers also need to read and write data frequently, but the memory size is sufficient and the amount of data is not large, you can use the memory to simulate the hard disk or cache the hard disk data to the memory. The memory is faster than the SSD. For example, I have one. Compile server, the frequently read and write compilation directory is a directory simulated by zram.
Of course, SSDs also have disadvantages. First, they are expensive. The same capacity is much more expensive than mechanical hard disks. Second, there is a limit on the number of writes. For applications with a particularly large write volume, you need to pay attention to the lifespan. The third is prolonged power failure. There is a risk of data loss.
In short, depending on the type of service, if it is io-intensive, it is best to use SSD, the performance improvement is very large, but it is necessary to make a record of the hard drive failure. If it is computationally intensive, use a mechanical hard drive, which is cheap and resistant.
If you must, please multiply your budget by 2. Otherwise, the operation will be fierce and you will lose your job if you lose data. Data redundancy backup must be done. Intel P series is highly recommended for data read and write IO.