Keep App Catalog running with Site Database server down & replica MP's in place
To improve HA options - this was previously filed on Connect (https://connect.microsoft.com/ConfigurationManagervnext/feedback/details/1413501/keep-app-catalog-running-with-site-database-server-down-replica-mps-in-place)
When running replica MP's policy is available on the replica MP's DB and Software Center is available and applications are able to installed even if the site server and DB is down. Great for device targeted deployments.
However for user centric deployments that are available via the App Catalog, the users ability to install these is none existent since when the site database is down the App Catalog cannot load as it tries to connect to it and fails.
It might be handy if the database elements that are needed to load the App Catalog are replicated over to the replicated DB's on the replica MP's and if the administrator is able to change from the site DB to a replica DB to keep the functionality of the App Catalog available during an outage.
Or even, if App Catalogs are offloaded from the site server then during their install the administrator is given the option to use a replica DB rather than the site database so no switching is needed during a site DB outage.