Each virtual or dedicated server has its own Os and works independently from the hosting servers of other clients. Updating the OS is usually overlooked, but doing that could have quite a lot of advantages for your sites. The most significant reason to employ the newest version is that patches are frequently released to repair security holes within the Os code, so if you do not install the updates, you risk individuals with harmful intentions to exploit these holes and to get access to your content. Operating system updates are also released for much better performance of the system in general and for far better compatibility with the hardware available on the market, which could instantly influence the efficiency of your sites. If the functionality and the security of your scripts is the reason to update them, you could also find out that their most up-to-date versions require an updated Operating System to be able to function effectively, so keeping the OS up-to-date is always a good idea.