There will be three different object forms in DAOS:
Hierarchical object
Hierarchical object in memory bucket
Flattened object
Hierarchical object can either be flattened, or keep the format and migrate to memory bucket. This diagram shows the status of DAOS objects, all elements in the blue rectangle are stored in DT-blob, they only consume memory during I/O processing, they can be evicted from DRAM if the system is under memory pressure. All the elements outside the rectangle are stored in MD-blob, it means that they stay in DRAM permanently when the pool is opened.
