Just wondering the necessity of having backups of the Secondary Members of a PI HA Collective. My PI System is located in 3rd party managed data centres with the servers (virtual machines) located in geographical locations distinctly separate from each other. With regular Collective Re-initialisations to keep the archives as valid as possible both servers will look fairly similar at all times. The incremental backup of the Primary Server (which in my opinion is the most critical) is carried out every 24 hours along with an incremental backup of the all PI VM images including the backup server. So as you can appreciate, the data is protected from Data Centre Failure and Physical Server Failure which leaves the possibility of total data loss extremely low. I see a few possibilities if the back files were required;
Failure of the Primary HA Member. Recovered and archives restored from the backup stored on the Backup Server which is in a different data centre.
Failure of the Secondary Member. Recovered, Reinitialised and Synchronised with the PI HA Collective Manager.
Failure of the Backup Server. Recovered with the backup regime implemented by the 3rd Party Data Centre Provider. Any gaps are filled from the Primary Archives through the PI Server Backup Process.
Now I realise that self managed servers without the level of redundancy that I have would validate the added security of having a backup of the Secondary Members but from what I have listed above is it really necessary to backup the Secondary Server?