When comparing CentOS vs SmartOS, the Slant community recommends CentOS for most people. In the question“What are the best host OSes for Docker?” CentOS is ranked 4th while SmartOS is ranked 7th. The most important reason people chose CentOS is:
CentOS favours stability over being up-to date. For this reason it ships with packages that may be up to two years behind in order to ensure stability over everything else. Using older versions for packages means that they have been thoroughly tested and used in production for quite some time, and are ensured to play well with each-other. This strategy has paid off quite a lot in the past. One example is the Heartbleed bug which left CentOS unaffected since it was using a two-year old OpenSSL library which did not have the bug.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Greatly favours stability over anything else
CentOS favours stability over being up-to date. For this reason it ships with packages that may be up to two years behind in order to ensure stability over everything else.
Using older versions for packages means that they have been thoroughly tested and used in production for quite some time, and are ensured to play well with each-other.
This strategy has paid off quite a lot in the past. One example is the Heartbleed bug which left CentOS unaffected since it was using a two-year old OpenSSL library which did not have the bug.
Pro Applications don't have to take into account potentially breaking changes in libraries
Since CentOS backports all updates and bug fixes to older versions in order to maintain package compatibility across releases, applications hosted on Red Hat Linux don't have to worry about potential breaking changes in libraries they use, especially language libraries.
Pro Good long term support
Pro Built-in disaster recovery solutions through clusters
CentOS has several built-in solutions for disaster recovery. For example, it comes with pacemaker which can be configured to manage multi-site and and stretch clusters across multiple geographical locations for disaster recovery and scalability. It can also be configured to trigger notifications when the status of a managed cluster changes by using enhanced pacemaker alerts.
Pro Supports multiple PHP versions
You can install multiple PHP versions and have them available for different users.
Pro Built-in support for containers
Comes with built-in management tools for containers (Atomic CLI, Cockpit) and a container runtime in the form of Docker engine.
Pro Great container isolation
SmartOS Zones provides excellent security through isolation on bare metal.
Pro Easy networking
Each container gets it's own IP and net stack.
Pro ZFS
Pro Bare metal containers
Pro dtrace
Cons
Con Not linux
Many users prefer the familiarity of Linux. (SmartOS comes from Open Solaris)