Stupid question I'm sure, but in an effort to limit the amount of necessary licenses, is monitoring the HA pair sufficient in lieu of monitoring the actual servers themselves?
Thanks!
There are no stupid questions @Junted Not sure if I'm understanding your question so feel free to provide more information on what you are trying to achieve, but generally you need 1 HA license for each server, if you want that server to be highly available. HA works as an active/passive pair with HA pools. So if you want to provide HA for 2 servers, you need 2 pools hence 2 HA licenses.
If you are talking about monitoring an AG cluster with DPA, it depends on how many AG's you got.
If you only have one Availability Group on two servers, I should monitor only the AG-itself. Resulting in one license.If you have more AG's than servers, I would monitor the servers themself instead.
If you only need to monitor the primary node in an AG, add it using the AG listener and DPA will follow it around as failovers occur. If you also want to monitor a read only node, add it using the listener as well but then in the JDBC Properties field under Advanced Properties use ApplicationIntent=ReadOnly as discussed here: Support for High Availability, disaster recovery - JDBC Driver for SQL Server | Microsoft Learn. DPA licenses are required for what you monitor, i.e. if you only monitor the primary then one license is used. If you monitor the read-only node, then another license is used.
If you're just looking for general health and 'up/down' status of the primary, monitoring the Listener with one license is perfect. But if your HA pair is doing a lot of heavy lifting on the secondary side (like reporting or backups), that second license is usually worth it just for the peace of mind of seeing the whole picture. Stick with the Listener for now and see if it gives you enough data!
