December 19, 2007
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OA23376 (DFSMS for z/OS 1.6+, OPEN 10Dec2007) - Missing
Records Using QSAM PUT to Write Data to an Extended Format Dataset. 07/12/03
PTF PECHANGE. A defect was introduced by APAR OA16854,
which applies to z/OS 1.6 through z/OS 1.8 and is also included in the
base z/OS 1.9 code. When using QSAM PUT to write data to an extended
format non-compressed physical sequential data set, the last few blocks
written before a close operation occurs are not physically written out
to the data set. The local fix is to remove OA16854 if you cannot
apply this maintenance. Flagged as PERVASIVE, DATALOSS.
1. Highlights of Cheryl Watson's TUNING Letter 2007 No. 6
2. New IBM Red Alert for QSAM
3. 2008 Collection DVD Available Soon
4. SHARE and zNextGen
5. Computer Snowflakes
1. Highlights of Cheryl Watson's TUNING Letter 2007 No. 6
The fifty-four page 2007 No. 6 TUNING Letter was emailed to subscribers on December 17, 2007. You may visit our Web site at http://www.watsonwalker.com to obtain single issues for $155 each. The following is a summary of just some of the contents of this latest TUNING Letter:
Processor Capacity Planning Tools
Given the amount of time and money required to upgrade a processor,
it's something that most organizations only do after much planning and
preparation. There are a number of tools available that should prevent
you from making wrong decisions, such as CPU Charts, system management
tools, and your own measurement systems. But wouldn't it be worth
a few hours of your time to verify your conclusions with another tool,
especially one that can be downloaded from IBM and installed at no cost?
Such a tool has been available for several years, and it has continued
to be enhanced. Even if you are not planning an immediate processor
upgrade, the tool is useful for answering many common capacity-related
questions. But our informal surveys show that only a small percentage
of organizations have used this tool, and that is unfortunate. On
page 31 of this issue you will find the first part of a two-part article
designed to provide more exposure for this useful resource. In this
article we tell you where to find the zPCR tool and related resources,
and describe some of the more recent enhancements. In a future issue,
the second part of the article will show you how to use zPCR to answer
some common questions related to processor capacity.
Reducing z/OS Overhead
We share two different reader experiences related to z/OS overhead
in the User Experiences section of this issue. As described on page
36, one reader reduced the uncaptured processor time dramatically by adjusting
some parameters and installing some maintenance. Then on page 44
you can read about a second reader who measured a dramatic drop in processor
consumption just by upgrading his z/OS release. Both readers were
kind enough to document their experiences well and pass them along to share
with you.
Monitoring Disk Performance and Space
Performance management tools such as IBM's RMF have always provided
facilities that allow you to monitor the status and performance of DASD
and other devices. But this monitoring has become more complex because
of features such as SMS and the zFS data sets used to manage UNIX data.
Some relief is on the way for those running RMF on z/OS release 1.7 or
later. In that release, RMF was enhanced to include four new reports
related to the monitoring of SMS storage groups and zFS data sets.
Samples of these reports and descriptions of their contents are included
in our article that starts on page 13. Two of these new reports allow
you to monitor SMS storage group space, while the other two allow you to
monitor zFS space and performance. One of the zFS reports also allows
you to request five different secondary reports that provide more detailed
statistics.
Elsewhere in this Issue
The IBM Red Alert that we mentioned in the last issue has now been
updated to include a more detailed description and another maintenance
recommendation. If your organization is running IMS 9.1, you should
get all the details on page 51. • There were some recent IBM enhancements
to the DS8000 storage device that are described on page 50. • On page 6
we mention some important maintenance that fixes incorrect values on some
of the RMF reports.
2. New IBM Red Alert for QSAM
On December 6, 2007, IBM created a new Red Alert warning of potential
data loss when using the QSAM access method to write data to an Extended
Format data set. Here is the description, as taken from the alert:
- ABSTRACT:
Potential Data Loss using QSAM PUT processing for Extended Format Data sets with PTFs for OA16854 applied.
DESCRIPTION:
A defect was introduced in APAR OA16854 PTFs UA33488 (z/OS 1.6),
UA33489 (z/OS 1.7) and UA33490 (z/OS 1.8) and base z/OS 1.9. A potential
for Data Loss can occur when using QSAM PUT processing on Extended Format
Data Sets. During close processing the last couple of blocks may
not be written out.
APAR OA23376 has been created to resolve this issue, see APAR text for additional details.
RECOMMENDED ACTIONS:
Remove PTFs UA33488, UA33489 and UA33490 or apply the fix for OA23376
when available, check APAR OA23376 for fix availability.
You can use the link http://www.ibm.com/servers/eserver/support/zseries to view the current Red Alerts. Just select 'Red Alerts for System z' from under the 'Popular links' heading to display the current entries. Once you are on this page, you can also register so that you will be sent an email when a new Red Alert is issued. We strongly believe that at least one person from every organization should be subscribed to this service.
3. 2008 Collection DVD Available Soon
We are currently building our 2008 collection DVD, and should have it in the mail to all TUNING Letter subscribers early next year. This yearly collection is sent to all subscribers at no additional cost, just as a bonus for our readers. 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 today. Most of the technical questions we receive can be answered with a quick search of the DVD.
There are also a number of bonuses on the DVD in addition to the TUNING Letters. You will also 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 and then get the DVD and the CPU Chart as part of the bargain.
There is also a whole section of 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. There are also some other useful documents, such as an 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 have a little money left in your 2007 budget, 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. If you are not a subscriber, please consider becoming one in 2008!
4. SHARE and zNextGen
It won't be that long until the next SHARE conference is upon us, because it is scheduled to be held February 24-29, 2008, in Orlando, Florida. February 29th does not roll around that often, so wouldn't it be fun to spend the day surrounded by like-minded friends in sunny Orlando?
You can find out more at the SHARE Web site (http://www.share.org), or by visiting http://orlando.share.org. You can register for both the conference and the hotel, and can find out more information about Orlando and the sessions to be presented. It's not too early to think about registering, or to get the approval process rolling in your organization. We plan to be there, and hope you can attend too.
Something we have mentioned often to our TUNING Letter readers is the zNextGen project. This is a fairly new SHARE project designed for those who are new to mainframe technology, either because they have just entered the workforce, or because they have been given new job responsibilities. This means that any age is welcome to join the project, although the majority of the members look to have been born after the System 360 was retired (how depressing). Even if you can't attend every SHARE (or if you can't attend at all), they provide valuable information and networking resources.
The zNextGen project sponsors just a few SHARE sessions, but they also coordinate with all of the other projects to recommend those sessions that should prove to be the most valuable to their members. They also provide some social connections, so that those new to SHARE and the whole mainframe culture will feel more welcome. Although the project has just been around for a few years, they have a membership of more than 350 people, representing more than 100 organizations and 10 different countries. Plus, there are many organizations (such as Watson and Walker) who are enthusiastic sponsors and mentors for the project.
So, if you think that SHARE is just a place for experienced system programmers, you need to get up to date. If there are people in your organization who are new to the mainframe, you need to get them involved. You can learn more about the zNextGen project through their Web page at http://www.share.org/Volunteer_Center/programs/zNextGen.cfm. Please do your part to support this great organization in Orlando and in future conferences.
5. Computer Snowflakes
Create your own snowflake at http://www.popularfront.com/snowdays. You can even save your creations and invite friends to view them.
We wish all of our readers a wonderful holiday season, and a great new year in 2008. Thanks for your friendship and loyalty over the years.
Stay Tuned!
Cheryl Watson
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