Physical storage space in a storage system is not allocated to a segment of a targeted volume until the segment of the volume is first targeted for storing write data. When write data is received, the storage system determines whether the targeted volume is designated for storing a first data type that is accessed frequently by I/O operations or designated for storing a second data type that is accessed less frequently than the first data type. Physical storage space for storing the write data is allocated from a first logical partition of the physical storage designated for storing the first data type when the targeted volume is of the first data type and from a second logical partition of the physical storage designated for storing the second data type when the targeted volume is of the second data type. Allocation of frequently accessed data is controlled and performance bottlenecking avoided.