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SMS: The Discipline

The basics of System Managed Storage.

System Managed Storage (SMS) has been an offering from IBM* since the late 1980's and early 1990's. IBM has offered many products that integrate under the Data Facilities Product (DFP), and there are offerings from other vendors. But, after over 15 years, there have been many questions that keep arising in the storage management area.

SMS, the product, does not provide an immediate solution to storage management issues, any more than having Java provides instant application solutions. There is a requirement for storage management disciplines, just as there is a requirement for programming disciplines.

The biggest stumbling block to managing storage is (as always) politics. As long as the user has access to the data, it's secure, and the performance characteristics make business sense, everything else is secondary.

Storage requirements have blossomed since the price plummeted in the 1990's but, as long as there is a non-zero cost, there will always be a need for the discipline, particularly since most shops are trying to do more with less and storage needs are growing.

Data security will not be addressed as part of this article, since the controls and audit requirements would cover more than the intended scope of this article.

Storage Groups

Storage groups used to be called DASD (or Disk) Pools, but with the introduction of SMS almost 20 years ago, IBM created new terminology. The largest introduction of overhead (manual and system) is caused by having too many storage groups - I've seen some shops with over 50! I believe there should be no more than eight, possibly ten. Also, I wouldn't separate based on dataset type, index, data, or other meaningless criteria. With the performance of today's sub-systems, and buffering, there is no need to separate on this basis.

Ted MacNeil is a capacity/performance analyst with more than 25 years in the IBM mainframe environment. Ted can be reached at



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