1. Cheryl Watson’s TUNING Letter 2004 No. 3
The forty-three-page 2004 No. 3 TUNING Letter was emailed to electronic subscribers last Friday. The print issues will be mailed later this week. You can purchase a printed copy of the current TUNING Letter for $95 at http://www.watsonwalker.com. The following “Management Summary” contains a summary of just some of the contents of this latest TUNING Letter.
SMF Type 30 Record Problems
In working with our BoxScore customers who are analyzing z990 performance, we have found some interesting anomalies with SMF type 30 (interval, step, job termination) CPU times and service units. Although this is not a specific problem associated with the z990s, their higher speed has simply magnified problems that have been brewing for the past decade. Consider that the type 30 record has been with us for some time, and was designed when processors were slower and the precision maintained was adequate. But as we have examined data from the z990 processors, we have found more and more situations where the lack of data precision makes it more difficult to uniquely identify jobs and to measure the resources those jobs actually consumed. This lack of precision may seem like a minor issue, but it has ramifications in all areas of system management – performance, capacity planning and chargeback. Please see our focus article on page 20 to read our analysis and recommendations.
We have several recommendations to IBM to correct the problem, plus recommendations to you for reducing the impact until IBM makes some changes. This is a problem that will continue to become more important as processor speeds continue to increase.
DB2 Version 8
It has been just slightly more than a year since IBM announced Version 8 of its DB2 product. But because this product has recently become generally available, we thought it might be good to review the features and prerequisites of this version, as a help to those of you who will be implementing it. This is the first version of DB2 designed for the z/Architecture environment and 64-bit mode execution. See our article on page 33 where we discuss the enhancements provided in this new release. We also report some preliminary performance numbers, and provide references to interesting presentations and resources that are available online.
OpenSSH on the z/OS Platform
Your installation probably uses tools such as Telnet and FTP to send data across networks. But did you realize these tools are not very secure, and send unencrypted passwords over the network? A new IBM tool may be a better solution, and it’s free. Read our summary of the OpenSSH (Open SecureShell) product announcement starting on page 40. This product was developed by the open source community, and is very popular on the UNIX and Linux platforms. Now the product is available to z/OS users and is fully supported by IBM.
Elsewhere in This Issue
In our Nuggets from the Forums section (starting on page 9), we explore high numbers of DB2 SMF records, internal reader allocation problems and suggestions for allocating large SAS work files. Our Q & A section continues to be one of the most popular sections of the TUNING Letter, as we answer some of the most common questions we receive from readers. In this issue we address questions regarding velocity goals, resource groups and the behavior of WLM on a uniprocessor. See these articles starting on page 30.