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Savings from Low-Overhead...
CSM Monitoring...
Our Authors:
Barry Graham has served in senior management for IBM and Hitachi Data Systems.
He is now a consultant working closely with the research organization Xephon, for whom he writes the
Mainframe Market Bulletin.
barryg@xephon.com
Jim Keohane is president of Multi-Platforms, Inc., which specializes in commercial software development/consulting with emphasis on cross-platform and performance issues.
jimkeo@multi-platforms.com
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Phil Norcross
SDS
Software Diversified Services, publisher of the Newsletter, is a leading provider of enterprise software to over 1,500 users worldwide. For more than 20 years SDS has built a reputation for superior, affordable products and reliable technical support.
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The Cost-Savings of Low-Overhead Software
by Barry Graham
CPU is costly, so is software that uses it.
Consider two competing software products:
one that uses 1% of CPU capacity;
another that uses 6% of CPU.
Over 5 years, the low-overhead alternative
will save $1 million to $7 million.
Throughout the mainframe's history, calculating the benefit of software that makes low demands on processor capacity has been a complex task for users and vendors alike.
It means calculating exactly when a processor upgrade would be necessary under two alternatives -- one assuming the low-overhead software product, and one assuming its higher-overhead alternative -- and then calculating the savings that result from choosing low-overhead software and delaying the processor upgrade.
The potential savings from delaying a processor upgrade are the following...
more...
CSM Monitoring: Buffer-Low Soldiers are Still Important, for New Reasons
by Jim Keohane
The Buffer-Low Soldiers are the unsung heros who watch for memory leaks and suspiciously large volumes of activity in z/OS CSM buffers. That wasn't their original training, but you know how it is in this business: We stay employed by updating our kit.
CSM (pronounced sha-zaaam!) is IBM's communications storage manager. It first appeared as part of HPDT (high-performance data transfer). Its goal is to avoid moving large chunks of data for VTAM, SNA, TCP/IP, and FTP. Instead, the data goes into CSM buffers and their ownership is passed among address spaces, applications, etc.
Think of lockers in a train station: When the key passes from hand to hand, ownership of the suitcases changes hands, without having to move the suitcases.
Lockers come in a range of sizes of course, small ones for purses, big ones for steamer trunks. Likewise, CSM buffers are allocated to accomodate messages of specific sizes. A 4K buffer holds messages up to 4 kilobytes in size, and so on. The available sizes are 4, 16, 32, 60, and 180 K.
If all the lockers are full, the station manager needs to add new ones. If the lockers sit mostly empty, the manager removes some of them. If the purse lockers are empty, but folks are lugging trunks from coffee shop to ticket counter to magazine rack, hopefully the manager will remove purse lockers and add trunk lockers.
A really ambitious manager might even swap lockers twice a day: purse lockers for commuters in the daytime, trunk lockers for big overnight business. At high-speed, it starts to look like the virtual gun racks in the Matrix movies.
So it is with CSM. Or at least was.
more...
Aug-Sept 2003...
Savings from Low Overhead...
CSM Monitoring...
Newsletter sponsored by SDS and VIP
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