Using cache with multi-tenant mid tier
With the introduction of multi-tenancy in midtier, there are additional cache categories introduced to optimize the cache footprint by sharing common metadata across the AR System servers. This helps improve scalability and performance of mid tier instance while using mid tier in multi-tenant mode.
Always use Sync Cache option to get any of your metadata changes reflected in mid tier. There should be no reason to use the Flush Cache option unless you see cache corruption (such as EOFException) in the mid tier logs due to an unclean shutdown or some other system issue. Using Flush cache hinders the mid tier performance as compared to using Sync cache and the performance-related issues multiply when running the mid tier in multi-tenant mode.