Upgrading OS in 3 Node Cluster
I plan to upgrade my Vertica server's OS and would like to better understand the "Operating System" limitation * (listed below) when replacing one host in a cluster.
I need to upgrade my Vertica server's operating system from CentOS 6.5 to CentOS 7.3. I planned to take out one of the 3 nodes and do a kickstart with the same Vertica version, but with new OS version. Then add it back to the cluster and wait for it to sync with the other 2 nodes. Once the sync is completed do the same for the second and third nodes. This way I upgrade the OS without having to do backup and restore.
1) Can a cluster work properly when for a short time some of the servers are CentOS 6.5 and some are 7.3?
2) When upgrading the OS one node at a time is it be much better to bring down my application server so no one will access the database at that time or it will only have a small performance affect?
3) Can backup taken on the same Vertica version but on CentOS 6.5 be restored on the same Vertica version on CentOS 7.3?
4) Is this the recommended way of upgrading the OS? I know there is an option for inline OS upgrade, but I was told by Linux experts that this is not recommended. Avoiding inline OS upgrade is also the recommendation of this forum?
The following taken from Vertica site *
You can replace the host with a new host that has the following same characteristics as the old host:
• IP address
• Operating system
• The OS administrator user
• Directory location
https://www.vertica.com/docs/9.2.x/HTML/Content/Authoring/AdministratorsGuide/ManageNodes/ReplacingANodeUsingTheSameNameAndIPAddress.htm?TocPath=Administrator's Guide|Managing the Database|Managing Nodes|Replacing Nodes|_____1