This is a short reminder that Red Hat Enterprise Linux (RHEL) version 6 will enter 'Extended Lifetime Support' in about 30 days from when I am writing this. Extended Lifetime Support (ELS) is a specific contract with Red Hat for them to cover certain security fixes for some extended time to allow sites some time for last minute transitions.
RHEL-6 was released in November of 2010, and was the first RHEL I got to work with/on after I returned to Red Hat in 2009. The release has seen 10 minor releases (1 less than RHEL-5), and has been in 'extended' mode since the last 6.10 release in June 2018.
When RHEL-6 enters its version of ELS, then it is considered 'end of life' by its 'downstream' rebuilders CentOS and Scientific Linux (and by extension EPEL). I am not sure what Scientific Linux plans are, but for CentOS, they will follow a similar plan as they did with EL-4/EL-5 distributions end. First they will copy all the code from the master servers to the vault servers. Then they will turn off the main mirrorlist systems any references to EL-6. This will cause the 'yum' command to fail and usually causes all kinds of yelling and screaming as people realize they needed to have moved their servers to something else before December 1, 2020.
For EPEL users it will be slightly different. All EPEL builds for EL-6 will be 'stopped' on December 1st. [Packages will no longer be allowed to branch to EL-6, builders will not be able to build code for EL-6. Packagers will not be able to move software from testing to prod.] At that point all RPMS on the download servers will be hardlinked to /pub/archive on the master servers. After a week, the mirrorlists will point to the archive zone, and Fedora Infrastructure will remove the code from /pub/epel/6/ trees.
Primarily, if you are going to be affected by the end of EL-6 services, you either need to get an ELS contract, move to another OS, or move to self-support. In order to self-support, you will need to mirror the source code from your distribution provider and learn the basics of RPM building. If you are on CentOS and find your servers not able to do yum installs anymore.. you will need to mirror the EL-6 from the CentOS vault somewhere locally and use that as your new 'mirror'. Depending on time and energy, I will try to outline some of these steps in future blog posts.
[references for article: https://en.wikipedia.org/wiki/Red_Hat_Enterprise_Linux#RHEL_6 ]