Team,
Is in place upgrade possible from CentOS 6 to 7 to 8 ? please suggest.
Thanks
Jay
in place upgrade CentOS 6 to 7 to 8
Re: in place upgrade CentOS 6 to 7 to 8
CentOS Linux 6 is dead. It did not have systemd.
CentOS Linux 7 will be dead by July 2024. It has systemd. Package manager (yum) is based on python 2.
There is no CentOS Linux 8 (any more). There are AlmaLinux 8, Rocky Linux 8, Oracle Linux 8, free RHEL 8 subscription, etc that did step in when CentOS Linux (8) died. Package manager (dnf) is based on python 3.
There is also AlmaLinux 9, Rocky Linux 9, Oracle Linux 9, free RHEL 9 subscription, etc. Its kernel requires x86_64_v2 microarchitecture features from CPU.
There has never existed supported in-place upgrade for CentOS.
RHEL has had some, but it does not work for all. Same applies to ELevate that AlmaLinux project created for el7->el8 and el8->el9.
The difference between 6 and 8 is drastic. You really want to configure 8 in the way the 8 should be configured, rather than praying that some automated conversion logic can interpret and translate your 6 config appropriately.
A setup has three parts: packages, config, and user data. Which packages are installed is also part of the config.
Hence, you should have config and user data. One should always have backups of those.
If the user data is currently clearly separate from the OS, then you can make a clean install of 8/9 without touching the data.
Just apply equivalent and appropriate config. If data is not separate, then you have to restore it from backup.
The user data might require some attention. For example, we had MariaDB on CentOS 7.
MariaDB has its own migration procedure. We did migrate it through 3-4 versions on the CentOS 7 before it could be transferred into Alma 9.
CentOS Linux 7 will be dead by July 2024. It has systemd. Package manager (yum) is based on python 2.
There is no CentOS Linux 8 (any more). There are AlmaLinux 8, Rocky Linux 8, Oracle Linux 8, free RHEL 8 subscription, etc that did step in when CentOS Linux (8) died. Package manager (dnf) is based on python 3.
There is also AlmaLinux 9, Rocky Linux 9, Oracle Linux 9, free RHEL 9 subscription, etc. Its kernel requires x86_64_v2 microarchitecture features from CPU.
There has never existed supported in-place upgrade for CentOS.
RHEL has had some, but it does not work for all. Same applies to ELevate that AlmaLinux project created for el7->el8 and el8->el9.
The difference between 6 and 8 is drastic. You really want to configure 8 in the way the 8 should be configured, rather than praying that some automated conversion logic can interpret and translate your 6 config appropriately.
A setup has three parts: packages, config, and user data. Which packages are installed is also part of the config.
Hence, you should have config and user data. One should always have backups of those.
If the user data is currently clearly separate from the OS, then you can make a clean install of 8/9 without touching the data.
Just apply equivalent and appropriate config. If data is not separate, then you have to restore it from backup.
The user data might require some attention. For example, we had MariaDB on CentOS 7.
MariaDB has its own migration procedure. We did migrate it through 3-4 versions on the CentOS 7 before it could be transferred into Alma 9.
Re: in place upgrade CentOS 6 to 7 to 8
Hi jlehtone,
Thanks for your time and details and one more question, are CentOS 8 Stream or CentOS 9 Stream good to have production ? or shall I go to AlmaLinux 9, Rocky Linux 9, Oracle Linux 9, free RHEL 9 subscription as suggested before ?
Thanks
Jay
Thanks for your time and details and one more question, are CentOS 8 Stream or CentOS 9 Stream good to have production ? or shall I go to AlmaLinux 9, Rocky Linux 9, Oracle Linux 9, free RHEL 9 subscription as suggested before ?
Thanks
Jay
Re: in place upgrade CentOS 6 to 7 to 8
No, Stream is a rolling prerelease (aka. beta) of the next RHEL point release.
Re: in place upgrade CentOS 6 to 7 to 8
Thank you Tunk!!.