February 15, 2009
 |
- Welcome to Cheryl's List!
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1. About Cheryl
Watson’s Tuning Letter 2008 No. 6
2. Our New 'Free
Tools' Section
3. IBM Red Alert
4. Clarification
to Tuning Letter 2008 No. 6
5. Our Annual
DVDs Have Been Mailed
1. About Cheryl Watson’s Tuning Letter 2008 No. 6
The forty page 2008 No. 6 Tuning Letter was emailed to paid subscribers on January 20th. You may visit our Web site at http://www.watsonwalker.com to obtain subscription information. The following is a summary of just some of the contents of this latest Tuning Letter:
SMF I/O Records
Most of this Tuning Letter is very
technical and concentrates on describing the I/O data available in almost
70 types of SMF records. Why are these important? They can
tell you such things as how much DASD space you have on the floor, how
much is used versus unused, how quickly it’s filling up, whether the tape
subsystem can handle the volume of activity, whether that activity increasing,
whether the DASD per-formance is improving or (more likely) degrading,
and which data sets are responsible for the greatest amount of I/Os.
You can use the data to tune those high-activity data sets to reduce the
I/Os, to tune OAM files (the most rapidly growing work in some installations),
to find out who deleted or updated library members, and much more.
In summary, we show you which metrics to track I/O usage at your site.
Normally it takes someone with a lot of experience to determine which of
those 70 record types to use. This issue should make the decision
easy for anyone.
During my research, I also noticed two new records and new fields in two others. These are only available in z/OS 1.10. In the type 42 record, you can identify who added or replaced a member of a PDS or PDSE (a need long requested by auditors). Type 74 (Device Activity) provides the volume capacity, and the type 19 record, which used to provide just unused space, now records total capacity as well. I like this new data.
System z Cooling
Problem
In order to prevent an outage due
to overheating, IBM has implemented a method of slowing the System z machines
down in order to cool the processor. Although there is an operator
message that identifies when this situation occurs, the data center management
and the users may not be aware of the degradation. In one site, the
ma-chine lost 25% of its capacity for eight hours. What would happen
in your installation if that occurred? Because the speed constant
is changed, but the pricing constant is not changed, you will also be overcharging
your customers for that period of time. Our User Experiences
section provides some suggestions.
Elsewhere in This
Issue
Our z/OS 101 section continues
to help introduce z/OS to newcomers. In this installment, we provide
the background data on those 70 SMF records concerned with I/O, which will
make our SMF Focus section more useful. In our Reader Feedback
section, we describe some positive experiences with HyperPAV and z10 compression.
2. Our New 'Free Tools' Section
We’ve just created a new section of our website called Free Tools. You’ll find a link at the left of our home page (www.watsonwalker.com). This section will contain freeware for use by anyone. We’ve moved our QuickStart Policy there, and have just added a new tool for reporting SMF subtypes.
Most installations use IBM’s programs to extract SMF records from either the SMF VSAM files (IFASMFDP) or SMF Logger files (IFASMFDL). The output from these programs shows the number and size of records by SMF type, but not by subtype. The type 42 record, for example, has over 20 subtypes. It’s becoming more and more important to understand the breakout of subtypes. The EWCP project at SHARE has sent a requirement to IBM to provide the subtype breakout. (We hope they’ll soon provide it.) Because we have been analyzing the SMF records in our multi-part series for our Tuning Letter, we see that the lack of understanding these subtypes makes managing the large SMF volumes even harder. We provide some alternatives in an article called ‘Obtaining SMF Counts’ and provide a SAS program to report the subtypes. Look in our new Free Tools section.
3. IBM Red Alert
- IBM issues Red Alerts for especially
important APARs. You may subscribe to their service at http://www14.software.ibm.com/webapp/set2/sas/f/redAlerts/home.html.
The following Red Alert (2008.01.29)
was released:
- Abstract: Updated CIFS Client Alert
for Customers: Final as of 1/15/2009
Description: Customers with IBM
Servers, including Power Systems, System i, System p, System x and System
z, running CIFS Client for Linux may experience unreported data inconsistencies
in the following conditions:
- Running CIFS Client for Linux
with caching enabled (default option) may experience data miscompares over
stressed or congested networks.
Running CIFS Client for Linux
with the 'forcedirectio' option set and with applications using the 'O_APPEND'
option.
In our Tuning Letter 2008 No. 6 (page 21), I included an IBM-Main item posted by Lizette Koehler describing a new ISPF option in z/OS 1.9. Lizette pointed out that the title on the article was wrong. It said ‘z/OS 1.9 SDSF Commands’ and should have said ‘z/OS 1.9 ISPF Option’. (The new ISPF option 3.17 displays UNIX line commands.)
5. Our Annual DVDs Have Been Mailed
We are pleased to announce that the 2009 edition of our DVD was mailed on February 12th and 13th. Current Tuning Letter subscribers should be receiving theirs within a week. This annual collection is sent to all subscribers at no additional cost. Not only does it contain all of the TUNING Letter issues for the past year, but also every issue we have published since publication started in 1991. Even though some of this issues were written years ago, it's amazing how much of the tuning advice still applies to-day. Most of the technical questions we receive can be answered with a quick search of the DVD.
With this mailing, we’ve gone as green as we can by no longer using jewel cases or bubble mailers, both of which are made from petroleum products.
There are a number of bonuses on the DVD in addition to the TUNING Letters. You will find our popular CPU Chart, which is useful when planning processor upgrades or comparing the speeds of different processors. Although you can purchase the CPU Chart as a separate item, most of our readers find it more cost effective to subscribe to the TUNING Letter so they’ll receive the DVD and the CPU Chart free of charge.
We’ve combined all of our z/OS 101 articles into a single document that can be given to those new to mainframe performance and capacity planning. (It’s also available at no charge on our Web site under ‘Articles’.) One section of the DVD is devoted to our presentations that were given at user groups such as SHARE and CMG, as well as technical articles that appeared in industry publications. You will also find all of our popular Cheryl's Hot Flashes sessions that have been presented at SHARE, going back to the first one that was given in 1998. And there are other useful documents, such as our SMF cross-reference card.
Please visit our Web site at http://www.watsonwalker.com to download or browse some past TUNING Letter issues and to learn more about subscribing. If you aren’t a current subscriber, please consider a subscription. For less than $3 per day, you can get a wealth of tuning information that may save your organization a great deal of time and money. Our subscribers are our biggest advocates, and we thank them for their loyalty!
Stay Tuned!
Cheryl Watson
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