Mainframe Capacity planning.

How to do Performance analysis and Capacity Planning for a shop. We also talk about Software Cost here.

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Ajay Pandit
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Mainframe Capacity planning.

Postby Ajay Pandit » Fri Jul 03, 2015 9:50 pm

Hi,

MIPS is usually used for LPAR level usage of a mainframe. And there is another thing called as SU, which is used to measure the amount service done by the infrastructure. But if I need to do a Capacity Planning for the underlying infrastructure of mainframes where can I start with? Can any of these (MSU, SU) be of some help to plan for that?



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Robert Sample
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Re: Mainframe Capacity planning.

Postby Robert Sample » Fri Jul 03, 2015 11:32 pm

Converting SU to MSU is real simple -- divide SU by 1 million and you'll get MSU (Millions of Service Units). Converting MSU (which is used much more than SU) to MIPS (and vice versa) can be done but it is not a simple conversion. IBM does not support the use of MIPS (or MSU for that matter) for capacity planning or performance management, although MIPS is still used by many sites. You can understand this by thinking about a site with a box having 16 processors -- some CP, some zIIP, some zAAP -- so the concept of "million instructions per second" doesn't consider how many processors are being used, nor how they are being used.

Capacity planning and performance management can be quite complex due to the potential questions involved -- is the processor capped? are there specialty engines used? how many LPARs are defined? how are the processors split between the LPARs? what weights are given the various LPARs? Furthermore, you need to consider not just TCB but also SRB and I/O time when looking at capacity and performance.

IBM has established a number of different benchmark workloads (batch, online, low I/O, medium I/O, high I/O, etc) that can be used to help with capacity planning. The site matches their workload characteristics against the different IBM workloads to find the best match, then uses that workload for their planning. Watson and Walker has some good material on capacity planning, and if your site has MXG installed then reading through some of the members of the MXG source PDS can be extremely helpful. Otherwise, you'll need to use Google and do some research.




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Re: Mainframe Capacity planning.

Postby Ajay Pandit » Sat Jul 04, 2015 10:24 am

Thanks Robert. I'm reading manuals to understand all these one by one. But would you like to recommend me to read a specific book ot ttorial so I that I can have better understading of what you have summed up here:

Capacity planning and performance management can be quite complex due to the potential questions involved -- is the processor capped? are there specialty engines used? how many LPARs are defined? how are the processors split between the LPARs? what weights are given the various LPARs? Furthermore, you need to consider not just TCB but also SRB and I/O time when looking at capacity and performance.



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Re: Mainframe Capacity planning.

Postby Robert Sample » Sat Jul 04, 2015 11:31 am

Start with the IBM Redbook ABC's of z/OS System Programming Volume 11 http://www.redbooks.ibm.com/redbooks/pdfs/sg246327.pdf which covers Capacity Planning, Performance Management, RMF, and SMF. Also visit the CMG (Computer Measurement Group) web site at http://www.cmg.org as they have lots of good information.




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Re: Mainframe Capacity planning.

Postby Gerhard_Adam » Thu Nov 26, 2015 7:29 pm

MSU's should never be used for capacity planning. SU's do NOT convert to MSU's because they represent two entirely different metrics. SU's are "charged" to specific units of work so that they represents a normalizing value to determine CPU or I/O usage. MSU's are defined as a capacity metric for software licensing purposes and do not reflect the actual service delivery capability of the machine.




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