A method for priority-based allocation in a storage pool involves receiving a request to write a data item in the storage pool, where the storage pool includes multiple metaslabs, and where each of the metaslabs includes a contiguous region of data. The method further involves determining a target metaslab selected from the multiple metaslabs by comparing multiple allocation priorities, where each of the allocation priorities is associated with one of the metaslabs, allocating a block to the target metaslab, and writing the block to the target metaslab, where the block includes a portion of the data item.