Single-Level storage

Single level storage in IBM i refers to a single unit of storage, not discriminated as primary storage(RAM) and secondary storage unit(Disk).

The operating system has addresses of all the objects and data pointing to it in the single large pool of virtual storage(known as system ASP or System Auxiliary Storage Pool).

No additional I/O is required by the processor to access any object which is stored in disk, as it is done by other systems which have dedicated RAM and secondary storages.

This is achieved by an address translator. All the storage spaces get treated as single pool of data. This enhances the turnaround time for retrieval of data from table, as well as any object such as libraries, programs, modules, binding directories and so on.

This is an auto tuning feature in IBM i for memory management and disk pooling optimization.

Any add-on to the disk capacity is readily available with optimized feature of single level pool.

There is no need to be concerned about particular disk drives filling up, or moving data from one disk to another to improve performance because all data management is taken care of by the licensed internal code. Licensed internal code also ensures that there is no disk fragmentation.

It saves time and planning for users to allocate disk spaces, IBM i storage manager will do this for you automatically. In USA, almost 80% of business are saving $60K – $160K annually as pay for a part-time or full-time system admin consultant.

It costs less amount of money for business to purchase a disk unit for IBM i rather than buying segregated units for RAM and secondary disk separately. Note that under some circumstances you might create additional storage pools that are called user ASPs and independent ASPs.