Database servers. Perhaps the most popular scenario of using servers accessible via local network or the Internet. Additionally, database servers can be connected to special application servers. Database servers shall simultaneously process numerous parallel requests from various users, thus, it makes low delay and high reliability important requirement to hard disk drives.
Streaming servers. They provide employees of a company or its clients with multimedia data. Users can access such data during a limited period of time as well as have 24/7 access (subject to system's availability via the Internet). This scenario undoubtedly requires fast hard disk drives. Servers should have the necessary speed and performance to make sure that large files are always available.
Virtualization servers – most growing direction in using servers. If five years ago one had to prove that this technology is future, today everything is about correct sizing. Installing a hypervisor and launching several virtual machines becomes an ordinary scenario. In this case servers play an important role – in reality they are application servers but because they have several running applications and operating systems, requirements to disk subsystem are even higher. Thus, for example, many virtualization software manufacturers have special requirements to types of disks.
Of course, such division into scenarios is quite conditional and many organizations apply combined scheme on their servers. In this situation it is recommended to allocate separate group of disks for each scenario, depending on its requirements to disk subsystem.
As mentioned before, not all hard disk drives designed to work on an ordinary PC or laptop can be used in servers due to special requirements. Difference of server hard disk drives may be in type of interface, capacity and internal components used. That is what determines the performance, reliability and energy efficiency of servers.
End of part II. For continuation, please see part III.