Sometimes there is not enough time to process you cubes. You will have to optimize processing. You can do many things.
- Try to separate different processes - break everything into smaller processing tasks. Then you will be able to tackle them individually. It will also allow you to more precisely orchestrate which task are you doing when.
- Separate processing of individual cubes.
- Instead of doing full processing of cube, do processing of data and processing of indexes (cube indexes and aggregations) separately. The first operation will involve you relational source, but the second one will use just SSAS. While SSAS server is busy you can do something else with relational engine/server.
- Try to manually set number of parallel tasks for cube processing. You may have better results. Note that you are not limited to numbers in the drop down list. You can type in other numbers.