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Are there any reasons NOT to run an Ubuntu server?
Why most of hosting providers use RedHat Enterprise and CentOS? What is the advantage of using them compared to, for example Ubuntu Server? For me it seems like its easier to install and configure ubuntu and also it is more frequently updated.
Enterprise grade Operating system gives you following, which is not found in non-enterprise class servers:
Other people have posted several good answers, but one that's missing so far is the main reason that, whilst I run Fedora on my desktops, I run CentOS on my servers, and that's a very long support lifetime. Fedora comes out every six months, and release n is supported until shortly after the release of n+2. That means I'll have to upgrade the OS once a year, and for a server, that's vastly too frequent.
CentOS follows Red Hat's model, which means four years of active support, two further years of bedded-in support, and one years after that of security-only support. Upgrading server OSes every seven years is fine; the hardware is usually being retired by that point.
An enterprise distro will commit to a very long, stable lifetime, and that's exactly what I want on a server.
Third party software support typically only supports the large commercial distros, like Redhat and SuSE (and by proxy their derivatives).
Established support, in the case of SuSE and Redhat.
Tools that are not available on the free versions of the operating systems that allow for easier management of large install bases.
That at least explains Redhat and SuSE, with their free variants getting some of the benefits by virtue of being derivative.
Also bare in mind that "frequently updated" is not always a good thing for large enterprise installations as it means a tremendous amount of QA. Stable tools with predictable release cycles is often preferred over cutting edge when it comes to thousands upon thousands of servers.
There is also a bit of a "traditional" way of thinking in installing Redhat, it's been the major player in enterprise linux for so long and one could easily some it up as "No one has gotten fired for buying redhat."
Easier for the end user is not always easier for the administrators.
I would add - hardware support (not only the drivers or procudents soft). You may not receive support from e.g. RAID controller vendor when you face troubles on "non-Enterprise" distros.
Also - often "easy" installation, a lot of packets comes for the price of stability. Usually Enterprise editions don't hung/reboot/crash without serious reason.
