You know that Linux is a hot data center server. You know it can save
you money in licensing and maintenance costs. But that still leaves the
question of what your best options 
are for Linux as a server operating system.
The Top 10 Linux server operating system distros ranked by ease of use, cost, available support and data center reliability.
We've
researched, crunched the numbers and put dozens of Linux distros
through their paces to compile our latest list of the top ten Linux
server distributions (aka "Linux server distros") — some of which you
may not be aware.
The following characteristics, in no particular order, qualified a
Linux server distro for inclusion in this list: ease of installation and
use, cost, available commercial support and data center reliability.
Without further ado, here are the top 10 Linux server operating systems for 2015:
1. Ubuntu 
At the top of almost every Linux-related list, the Debian-based
Ubuntu is in a class by itself. Canonical's Ubuntu surpasses all other
Linux server distributions — from its simple installation to its
excellent hardware discovery to its world-class commercial support, Ubuntu sets a strong standard that is hard to match.The latest release of Ubuntu, Ubuntu 15.04 "Vivid Vervet," debuted in April 2015 and ups the ante with OpenStack Kilo support and Snappy, an optimized packaging system developed specifically for working with newer trends and technologies such as containers, mobile and the Internet of Things (IoT).
Ubuntu's Long Term Support (LTS) version, which is released every two years and includes five years of commercial support for the Ubuntu Server edition, was last updated in April 2014 as Ubuntu 14.04 LTS.
2. Red Hat Enterprise Linux 
While Red Hat started out as the "little Linux company that could,"
its Red Hat Enterprise Linux (RHEL) server operating system is now a
major force in the quest for data center rackspace. The Linux darling of
large companies throughout the world, Red Hat's innovations and
non-stop support, including ten years of support for major releases,
will keep you coming back for more.RHEL is based on the community-driven Fedora, which Red Hat sponsors. Fedora is updated more frequently than RHEL and serves as more of a bleeding-edge Linux distro in terms of features and technology, but it doesn't offer the stability or the length and quality of commercial support that RHEL is renowned for.
In development since 2010, Red Hat Enterprise Linux 7 (RHEL 7) made its official debut in June 2014, and the major update offers scalability improvements for enterprises, including a new filesystem that can scale to 500 terabytes, as well as support for Docker container virtualization technology. The most recent release of RHEL, version 7.1, arrived in March 2015.
3. SUSE Linux Enterprise Server 
The Micro Focus-owned (but independently operated) SUSE Linux
Enterprise Server (SLES) is stable, easy to maintain and offers 24x7
rapid-response support for those who don't have the time or patience for
lengthy troubleshooting calls. And the SUSE consulting teams will have
you meeting your SLAs and making your accountants happy to boot.Similar to how Red Hat's RHEL is based on the open-source Fedora distribution, SLES is based on the open-source openSUSE Linux distro, with SLES focusing on stability and support over leading-edge features and technologies.
The most recent release, SUSE Linux Enterprise Server 12 (SLES 12), debuted in late October 2014 and introduced new features like framework for Docker, full system rollback, live kernel patching enablement and software modules for "increasing data center uptime, improving operational efficiency and accelerating the adoption of open source innovation," according to SUSE.
4. CentOS 
If you operate a website through a web hosting company, there's a
very good chance your web server is powered by CentOS Linux. This
low-cost clone of Red Hat Enterprise Linux isn't strictly commercial,
but since it's based on RHEL, you can leverage commercial support for
it.Short for Community Enterprise Operating System, CentOS has largely operated as a community-driven project that used the RHEL code, removed all Red Hat’s trademarks, and made the Linux server OS available for free use and distribution.
In 2014 the focus shifted following Red Hat and CentOS announcing they would collaborate going forward and that CentOS would serve to address the gap between the community-innovation-focused Fedora platform and the enterprise-grade, commercially-deployed Red Hat Enterprise Linux platform.
CentOS will continue to deliver a community-oriented operating system with a mission of helping users develop and adopt open source technologies on a Linux server distribution that is more consistent and conservative than Fedora's more innovative role. At the same time, CentOS will remain free, with support provided by the community-led CentOS project rather than through Red Hat. CentOS released CentOS 7 in March 2015, which is derived from Red Hat Enterprise Linux 7.1.
5. Debian 
If you're confused by Debian's inclusion here, don't be. Debian
doesn't have formal commercial support but you can connect with
Debian-savvy consultants around the world via their Consultants
page. Debian originated in 1993 and has spawned more child
distributions than any other parent Linux distribution, including
Ubuntu, Linux Mint and Vyatta.Debian remains a popular option for those who value stability over the latest features. The latest version of Debian, Debian 8 "jessie," debuted in April 2015, and will be supported for five years. Debian 8 marks the switch to the systemd init system over the old SysVinit init system, and includes the latest releses of the Linux Kernel, Apache, LibreOffice, Perl, Python, Xen Hypervisor, GNU Compiler Collection and the GNOME and Xfce desktop environments.
6. Oracle Linux
If you didn't know that Oracle produces its own Linux distribution, you're not alone. Oracle Linux (formerly Oracle Enterprise Linux)
is Red Hat Enterprise Linux fortified with Oracle's own special Kool-Aid as well as various Oracle logos and art added in.Oracle's Linux competes directly with Red Hat's Linux server distributions, and does so quite effectively since purchased support through Oracle is half the price of Red Hat's equivalent model.
Optimized for Oracle's database services, Oracle Linux is a heavy contender in the enterprise Linux market. If you run Oracle databases and want to run them on Linux, you know the drill: Call Oracle. The latest release of Oracle Linux, version 7.1, arrived in March 2015 and is based on RHEL 7.1.
7. Mageia / Mandriva
Mageia is an open-source-based fork of Mandriva Linux that made its
debut in 2011. The most recent release, Mageia 4, became available in
February 2014, and Mageia 5 is expected in mid-2015.For U.S.-based executive or technical folks, Mageia and its predecessor Mandriva might be a bit foreign. The incredibly well-constructed Mandriva Linux distribution hails from France and enjoys extreme acceptance in Europe and South America. The Mandriva name and its construction derive from the Mandrake Linux and Connectiva Linux distributions.
Mageia maintains the strengths of Mandriva while continuing its development with new features and capabilities, as well as support from the community organization Mageia.Org. Mageia updates are typically released on a 9-month release cycle, with each release supported for two cycles (18 months). As for Mandriva Linux, the Mandriva SA company continues its business Linux server projects, which are now based on Mageia code.
8. ClearOS 
ClearOS is an open-source Linux operating system based on Red Hat
Enterprise Linux and CentOS that combines a server, network and gateway
plaform. Formerly called ClarkConnect, ClearOS has gained traction as a
viable Linux server option, particularly in the small business market.
With its highly touted administration interfaces and superior
documentation, ClearOS serves as an ideal option for less-experienced
admins or for anyone looking to get up and running on a Linux server OS
quickly and without a lot of fuss.ClearOS offers a free, open source Community edition as well as an inexpensive Professional version that includes a range of support options and additional features. The Clear Foundation maintains ClearOS and the ClearCenter Marketplace, which serves as an app store with both free and paid apps for extending the capabilities of ClearOS.
The latest release of ClearOS, ClearOS 6.6, became available for download in February 2015. The ClearOS 6 series offers new apps and features such as 64-bit support, a graphical installer, QoS for prioritizing network traffic, network mapping and the ClearCenter Marketplace.
9. Arch Linux 
A simple, lightweight Linux distribution, Arch Linux is definitely
designed with more competent Linux users in mind. Arch Linux doesn't
provide the level of support and ease of use that other Linux server
operating systems offer, but that doesn't mean it can't be used as a
viable server for more experienced administrators. Those interested in
giving Arch a spin as a streamlined server are encouraged to start with
the Arch Linux Server site.Like the Gentoo Linux distro, Arch Linux utilizes a rolling release model, which means regular system updates are all that are needed to keep current with the latest Arch Linux components and packages. Arch Linux's home-grown 'packman' package manager provides updates to the latest software applications with full dependency tracking, and Arch Linux updates tend to follow the pace of Linux kernel releases in order to provide optimal hardware support.
