In this issue, I’ll cover the following:
1. Correction on HDS Processor
2. Important Clarification on LE
3. New Amdahl Processors
4. Important Caution on Daylight Savings Time & Sysplex Timers
1. Correction on HDS Processor
In our last Cheryl’s List, we included some new HDS processors. The Pilot B8S model was listed as having 8 CPs. It should have said 11.
2. Important Clarification on LE
In last week’s Cheryl’s List #15, I gave a summary of the contents of my TUNING Letter No. 4, which is devoted to information on Language Environment. Even though this information is less than a week old, both IBM and I have started to get reactions from our mutual customers. In my letter, I mentioned that “some installations see a 5% to 30% increase in CPU usage after migration to LE.” (I have since qualified that sentence in the archives copy.)
I want to make it clear that this increase occurs if customers do NOT tune the LE run-time options and do NOT apply performance APARs mentioned in my newsletter. This potential for overhead is true when migrating to any new product on any platform. TUNING is key if you want to reduce CPU usage for any product. Please read my newsletter in its entirety and follow both IBM’s and my recommendations. This will not only help you to migrate to Language Environment but also help reduce CPU usage when using LE.
I also noticed that this point was not made clearly enough in the newsletter itself. If you are a subscriber, please pass this information on to others in your organization who may be seeing the LE articles.
3. New Amdahl Processors
On October 12, Amdahl announced their Millennium GS800 series of CMOS processors. They announced 16 new base models (based on 102, 114, 122 MIPS uni-processors with some degraded models) and 8 additional models that are available as upgrades. In addition, by using MSF (Multi-Server Facility) to partition these models into smaller processors, organizations will be able to configure an additional 18 options. The 12-way turbo, GS8Z8, will deliver about 1075 MIPS. Early shipments will begin in December 1998 instead of 1999 as originally indicated, with the faster turbo models being shipped in February 1999.
For additional information, software groups, and MSUs, see the Amdahl home Web page at http://www.amdahl.com, then select “Millennium 800 Servers”, then download the ”Millennium Servers 800 Series Specification Sheet” PDF file.
We had been planning to send out an updated CPU Chart to our Newsletter subscribers with the last issue (mailed October 13th), but have delayed the mailing of the CPU Chart until next week to add these new models. If subscribers need a list of the new processors before that, they can send their company name, address, and fax number to admin@watsonwalker.com.
4. Important Caution on Daylight Savings Time & Sysplex Timers
Bob Archambeault, whom subscribers will recognize as the author of our CICS Performance series, wants to provide this notice about the upcoming daylight savings time change (October 25th):
In a sysplex environment, the sysplex timer clock should NEVER be turned backward. The proper way to handle local time changes is to use GMT as a standard and change the local time offset from GMT (i.e. don’t specify GMT=LOCAL). If you do set the sysplex timer clock back, you’ll first get a warning saying that a sysplex-wide IPL is required. Unfortunately, some people choose to ignore the warning and problems may occur. For example, CICS TS transaction logs (which use the system logger) have a difficult time with this, and CICS will go into a loop for the entire hour until the time catches up. If you really want to set the clock back (against IBM’s advice), the only resolution to the CICS problem is to delete and redefine the log structures. Bob has heard of similar situations where people have set the time back on a Y2K LPAR and caused CICS to go into the same loop.
Additional documentation may be found in the following manuals:
GA23-0365 – Planning for the IBM 9037 Sysplex Timer
GG66-3264 – IBM 9037 Sysplex Timer & S/390 Time Management
That’s all for now. Stay tuned!