Ahoy @gdolidze,
Interesting question indeed.
Looking at this from a more foundational level, you might be best served making a new server.
[UPGRADING FROM RHEL 6 TO RHEL 7](
https://access.redhat.com/documentation ... el_7/index)
* must be RHEL 6.10 minimum
* must be x86_64 (64 bit), not x86 (32 bit)
* more details in the OS vendor guide
Just after entering Chapter 1:
```
**Supported groups of packages: Only packages from the following groups can be installed on the system before an in-place upgrade:**
Minimal (@minimal)
Base (@base)
Web Server (@web-server)
DHCP Server
NFS File Server (@nfs-server)
Print Server (@print-server)
CIFS file server
NOTE
Although upgrades of other packages and groups are not supported, certain packages can be uninstalled from the RHEL 6 system and reinstalled on the upgraded RHEL 7 system.
```
I would suggest you are likely to save more headache and OT by spinning up a fresh RHEL7 box, and migrating your installation over.
[Backing Up And Restoring Your Nagios XI System](
https://assets.nagios.com/downloads/nag ... ios-XI.pdf)
I have leveraged the steps in this guide to run APP fail-over (in name only, not using any sort of clustering automation type stuff).
In fact I am manually orchestrating the effort, including taking the backup, shipping it over to the "cold side", restoring the data onto the new node, turning up / turning down XI nodes for APP service, etc.
The APP backup contains an extract of the APP structures & data on the FS, and includes a dB dump (mysqldump, as I recall).
In this way, one might reasonably take one of these backups, and use it to spin up an identical copy / instance of the source XI instance (EG: for triage, audit, disaster recovery, etc.)
All of that said, not clear how a difference in OS version plays into this (have not done this).
I suspect dB versions would have to align, and I recall SUPP mentioning XI version must be aligned (at least for MAJOR.MINOR.x, and hope SUPP will correct me if inaccurate).
I expect our friends with the APP VENDOR will have more specific insight on this.
Regardless of the path chosen, good luck!
