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We are running Cassandra, specifically Datastax's Enterprise version in our production CentOS environment.

As such, I wanted to upgrade our machines from an older CentOS 6.3 version to 6.5, the reason I don't want to upgrade all the way to 6.6 is that Datastax has not certified that version yet - and since this is our production environment I'm not willing to take even a small risk of something not working correctly with 6.6.

How can I update just to Centos 6.5, if I run yum update it will bring me up to 6.6 I believe?

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CentOS purposely does not have a mechanism for holding steady on an old point release.

The point release numbers used for CentOS 6 and earlier generally do not refer to new features, as with most other software. They simply mark the times during CentOS' long release cycles where they batched up the bug fixes and security fixes made to their RPMs and mastered a new set of installation media.

(In fact, starting with CentOS 7, they've abandoned the point release numbering entirely, adding a date code to differentiate new installation media releases.)

If you said yum update on a CentOS 6.0 system on the day CentOS 6.1 came out, the difference between your upgraded CentOS 6.0 system and a fresh 6.1 installation would be very small.

The primary difference between CentOS 6.5 and CentOS 6.6 is a whole pile of bug fixes and security patches. There are typically very few functional changes between such point releases.

It is better to think of yourself as running "CentOS 6" rather than "6.5." The only question is whether you're up-to-date on your fixes or not.

The whole point of using a "stable" Linux like CentOS is that they purposely do not make any functional changes they don't absolutely have to within the major release series. No configuration file formats change, no configuration changes need to be made to use the newly-fixed packages. The software you originally installed with the OS just works better now.

Therefore, I recommend that you do not hold steady on any CentOS point release. Keep your systems up to date! That is how you get security fixes.

There are a very small number of exceptions to the "no new features" policy. Some examples:

  • They don't seem to keep Firefox held back to an old feature release, for example, probably because it becomes too difficult to back-port security fixes after some point.

  • Red Hat will occasionally add some new non-breaking feature; they took XFS out of beta status in RHEL 5 and 6 shortly after RHEL 7 shipped, since XFS is the default filesystem in RHEL 7. If you were eschewing XFS in these older OSes because it was considered beta at the time you installed the OS, this effectively means those older machines got a new feature in the middle of the active maintenance cycle. (I believe this happened with CentOS/RHEL 5.10 and 6.5.)

    This status change didn't affect your non-XFS filesystems, though, so it is not a problem from a stability standpoint. Only those who were happily using XFS in its beta state cared about the change.

Given that CentOS 6.6 came out about nine months ago now, I don't see why you're waiting on Datastax's approval. Unless you have specific information from them that a particular package is incompatible, I wouldn't keep holding your breath waiting on their approval.

RHEL 6.7 entered beta about two months ago, so it should be appearing soon. CentOS 6.7 should follow in two or three weeks. That means there's a good chance that if you hold off on 6.6, you'll be two releases behind current soon.

If you're still feeling nervous, roll the change to one machine, then two, then four, etc., doubling until all machines have the change.

  • Just to add that I've come across a couple of situations where I have been unable to upgrade to the latest point release: 1. A project has blindly agreed to everything the vendor has asked for and the vendor claims to only support a specific point release. 2. A new point release is rolled out, but has yet to pass internal acceptance testing (e.g. I understand RHEL 6.7 breaks some Veritas stuff, so the powers that be in my organisation have yet to accept it) – forquare Aug 26 '15 at 14:49
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Warren Young's answer covers all the reasons you probably you probably don't want to and probably don't need to do this so please read it. But if you really have to and you really understand what you're doing, this command should do it for you:

yum --disablerepo=* --enablerepo=C6.5* upgrade

Basically it disables all the repos on your box and enables the repo CentOS 6.5 repo specified in /etc/yum.repos.d/CentOS-Vault.repo and runs the upgrade command so you're only getting whatever the latest stuff in CentOS 6.5 was.

If you need to have some other repos enabled during the upgrade process, add more --enablerepo=foo options to the yum command.

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    +1 for answering the actual question, but it would be a crying shame if the OP accepted this answer. To do so would be to say, "Yes, I really do want to leave my boxes running known-insecure software." – Warren Young Jun 30 '15 at 0:16

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