On 02/16/2015 10:29 AM, Jegadeesh Kumar wrote:
I am working on linux environment. we have centOS servers which is running on CentOS 6.2. So far i didn't work on upgrade OS to higher version. That's why i asked this question.
I know yum upgade will update the packages that installed on the server. Any way let me try um upgrade and update you.
Every time this comes up, I try to explain how CentOS numbering works and how CentOS works in general.
In CentOS, there is CentOS-5, CentOS-6 and CentOS-7. The minor versions, or point releases as we call them, like 5.11, 6.6, 7.0.1406 ... are all just "POINT IN TIME" releases of the major CentOS branch you are on.
These "POINT IN TIME" releases are NOT designed to be consumed out of band. In reality, being on CentOS-6.2 when CentOS-6.3 is available means you are missing security updates as 6.3 is just 6.2 and all current updates.
If you have any CentOS-6.x release installed and if you run a "yum update" without changing anything then you will get the latest update set for CentOS-6 .. which is currently 6.6 plus updates. That is the only version of CentOS-6 that is in any way tested and it is the only version that might be somewhat secure. Any other CentOS-6 version is missing security updates.
It is just like Windows 7 and Service Packs. If you have Windows 7, you SHOULD have the latest Service Pack installed. If you don't that is an unsupported option and you have security issues. You can have Windows 7, Windows 8 or Windows 10 and be secure, but you must be running the latest service packs on each of those to be secure. If you are running Windows 7 without any service packs, that is a very bad thing.
Same for CentOS .. you can be running 5, 6, or 7 .. but you need to be running the latest snapshot in that tree to have all the security updates .. and unless you (or your provider) are trying really hard, running any updates set will take you to the latest version in your branch.
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