Thanks Tug. I think I wasn’t clear in what I wanted. I want to use Couchbase a a caching tier for .NET applications using SQL Server or Oracle as database systems. AppFabric 1.1 enables read-through and write-behind using a user-defined provider. That makes programming very easy (just access the cache). I had that in mind. I know that it can lead to problems (the provider can fail, write is deferred what could cause item loss if the cluster goes down a.s.o.). But if the provider is carefully implemented and tested it works. NCache obviously enables read-through and write-behind as well, but I did not check that yet. If I had to implement that myself (in the data access layer), read-through would not be a problem, but write-behind is not so easy considering deferred database updates to avoid heavy database load.