Sql-server – Updating Always On Availability Group server connected to Windows SQL Cluster

1. I would only use RAID 0 for the logs if you're okay with having reduced disaster recovery capability. You won't be able to make log tail backups in the event of a disk failure, and will only be able to restore to your most recent backup. However, this may be less of an issue if you're running Availability Groups, particularly with synchronous mirroring. You generally won't have any performance overhead for RAID 1 vs. a single non-RAID disk, but you will have better I/O performance with RAID 0 instead of RAID 1 for an equal number of disks.

2. Be aware that tempdb also has both data files and log files, and those could end up interfering with each other (performance wise) if placed on the same volume. You may want to consider foregoing the spare disk and using it for tempdb logs instead if performance still isn't acceptable. If your C: array is large enough, you might be able to get away with using it for on-disk backups, though you should probably partition it to prevent runaway backups from filling your OS disk.

The only possible concern in your setup is the Availability Mode and Failover option. If your virtual machines are in the same datacenter or relatively close geographically with a good connection between them you should look into using Synchronous-commit mode and Automatic Failover for the best recovery scenario with no data loss and minimal downtime, especially if it fails during a time it may be difficult to get someone to manually fail it over.

If they are they significantly geographically apart and connectivity isn't reliably 'good' then your setup is fine unless data loss is considered catastrophic. The Asynchronous route is primarily for use when performance is sporadic or far from guaranteed.

While specifying the connection has some value, it may be overkill in such a setting if for some reason your reporting application loses connectivity to the Secondary Replica. There is no reason it couldn't report off the Primary Replica aside from any possible performance concerns, but that may be a valid enough reason to insure the Primary denies the connection.