Million service units
Encyclopedia
A million service units is a measurement of the amount of processing work a computer
can perform in one hour. The term is most commonly associated with IBM mainframes.
One “service unit” originally related to an actual hardware performance measurement (a specific model’s instruction performance). However, that relationship disappeared many years ago as hardware and software evolved. MSUs are now like other common (but physically imprecise) measurements, such as “cans of coffee” or “tubes of toothpaste.” (Cans and tubes can vary in physical size depending on brand, market, and other factors. Some coffee cans contain 13 ounces and others 500 grams, for example.)
Most mainframe software vendors charge by MSUs consumed (“workload-based charging”) or by total MSU system capacity. Thus, while MSU is an artificial construction, it does have a direct financial implication. In fact, software charges are why the MSU measurement exists at all.
IBM
publishes MSU ratings for every mainframe server model, including the zSeries
and System z9
ranges. For example, a zSeries z890 Model 110 is a 4 MSU system. MSU ratings are always rounded to whole numbers. IBM enforces an MSU rule called the “technology dividend
”: each new mainframe model has a 10% lower MSU rating for the same level of system capacity. For example, when IBM introduced the System z9
-109 in 2005, if a particular z9 configuration could process the same number of transactions per second as its predecessor (a particular z990 configuration) then it would do so with 10% fewer MSUs. The lower MSU rating means lower software costs, providing an incentive for customers to upgrade.
However, as software costs are not linear with MSUs, decreasing or increasing MSUs will not show a proportional change in software costs. The "least expensive" MSUs will be added (with increased MSUs) or removed (with decreased MSUs). For example, a 10% increase in MSUs will result in a software cost increase of less than 10%. How much more (or less, if reducing MSUs) depends on numerous other factors.
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
can perform in one hour. The term is most commonly associated with IBM mainframes.
One “service unit” originally related to an actual hardware performance measurement (a specific model’s instruction performance). However, that relationship disappeared many years ago as hardware and software evolved. MSUs are now like other common (but physically imprecise) measurements, such as “cans of coffee” or “tubes of toothpaste.” (Cans and tubes can vary in physical size depending on brand, market, and other factors. Some coffee cans contain 13 ounces and others 500 grams, for example.)
Most mainframe software vendors charge by MSUs consumed (“workload-based charging”) or by total MSU system capacity. Thus, while MSU is an artificial construction, it does have a direct financial implication. In fact, software charges are why the MSU measurement exists at all.
IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
publishes MSU ratings for every mainframe server model, including the zSeries
ZSeries
IBM System z, or earlier IBM eServer zSeries, is a brand name designated by IBM to all its mainframe computers.In 2000, IBM rebranded the existing System/390 to IBM eServer zSeries with the e depicted in IBM's red trademarked symbol, but because no specific machine names were changed for...
and System z9
System z9
IBM System z9 is a line of IBM mainframe. It was announced on July 25, 2005 and the first models were available on September 16, 2005. The System z9 also marks the end of the previously used eServer zSeries naming convention, and it is the last z/Architecture 1 machine.- Background :System z9 is a...
ranges. For example, a zSeries z890 Model 110 is a 4 MSU system. MSU ratings are always rounded to whole numbers. IBM enforces an MSU rule called the “technology dividend
Technology dividend
Technology dividend is an IBM term referring primarily to the lower software costs that accrue, ceteris paribus, when upgrading from one zSeries or System z9 server model to the next generation ....
”: each new mainframe model has a 10% lower MSU rating for the same level of system capacity. For example, when IBM introduced the System z9
System z9
IBM System z9 is a line of IBM mainframe. It was announced on July 25, 2005 and the first models were available on September 16, 2005. The System z9 also marks the end of the previously used eServer zSeries naming convention, and it is the last z/Architecture 1 machine.- Background :System z9 is a...
-109 in 2005, if a particular z9 configuration could process the same number of transactions per second as its predecessor (a particular z990 configuration) then it would do so with 10% fewer MSUs. The lower MSU rating means lower software costs, providing an incentive for customers to upgrade.
However, as software costs are not linear with MSUs, decreasing or increasing MSUs will not show a proportional change in software costs. The "least expensive" MSUs will be added (with increased MSUs) or removed (with decreased MSUs). For example, a 10% increase in MSUs will result in a software cost increase of less than 10%. How much more (or less, if reducing MSUs) depends on numerous other factors.
Sample usage
- “Our accounting department will need 6.5 MSUs on a System z9-109 from 10 p.m. to 1:00 a.m. each night in order make sure our quarterly financial statements arrive on time.”
- “You will need 8 more DB2IBM DB2The IBM DB2 Enterprise Server Edition is a relational model database server developed by IBM. It primarily runs on Unix , Linux, IBM i , z/OS and Windows servers. DB2 also powers the different IBM InfoSphere Warehouse editions...
MSUs for your z900 to handle this year’s Christmas sales rush. Since your current z900 configuration doesn’t have enough capacity to add 8 DB2 MSUs, you need to add another engine. It might be less expensive to upgrade to a z9 because of the double technology dividend.”
External links
- Sample MSU Figures for various hardware configurations (IBM Website)
- Isham Research (republishes MSU figures)