Hi All

I am trying to upgrade CentOS 6.6 yo 7.3. however couldnt find any relevant good information on the same. I cant see correct upgrade path to do the same.

BR
Kj

CentOS 7.4 is the latest version of it out.

Unless you have some settings that you wish to keep, I would suggest you do a clean install instead.
Also, upgrading from 6.6 to 7.3 might be difficult, to say the least. As, I think the reason your having trouble finding any good doc's on it, is because you may not be able to "upgrade" version 6.6 to 7.3

You may also want to read this: https://linuxaria.com/article/an-int...d-for-centos-7

I think you'll find that the above link is going to be a good reason as to why, it will be difficult (if possible at all) to upgrade from 6.6 to 7.3

Never having tried it, I would be prepared to bet you have to be at the latest (updated) CentOS 6 level and can only upgrade to the latest CentOS 7 level.
Just a guess.

There isn't an in place upgrade tool for migrating to version 7. As suggested you should backup your data and perform a clean install.

https://wiki.centos.org/TipsAndTricks/CentOSUpgradeTool

You should have read the upgrade information about RHEL. CentOS is built from that same sources as RHEL, and the same information applies.

The ONLY update path between major version numbers for RHEL (and CentOS) is the full upgrade install method:
Back up critical settings
Record additional software package list
Back up critical data
Perform a full install of the new version (overwriting and destroying the old one)
Install additional software
Restore critical settings
Restore critical data

There are ways people have found to short-cut the process, but most of those depend upon your having planned for this day when you did the original install. All of them require full backups or cloning, because a botched upgrade can result in a unusable system and complete data loss.