Latest Entries

z/Data Perspectives: What Is Large?

Every now and then, some sage consultant will offer advice such as “Large DB2 tablespaces should be partitioned” or “Bind your DB2 applications using ACQUIRE (ALLOCATE) and RELEASE(DEALLOCATE) for high-volume transaction workloads.” But how useful is this advice? What is meant by large and high volume? Terms such as these are nebulous and ever changing. Just what is a large database today?…

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In 1878, a 19-year-old Polish student named L.L. Zamenhof introduced his attempt to bridge the language chasms created over the centuries with a language he called Esperanto. At this point in Zamenhof’s brief lifetime, Poland was a part of the Russian empire, and his town’s population was comprised of four major ethnic groups: Russians, Poles, Germans and a large group of Yiddish-speaking Jews. Zamenhof was described as saddened and frustrated by the many quarrels between these groups. He supposed that the main reason for the hate and prejudice lay in mutual misunderstanding, caused by the lack of one common language that would play the role of a neutral communication tool between people of different ethnic and linguistic backgrounds…

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Once upon a time, a 3390 Model 3, with 2.8GB of storage capacity (3,339 cylinders of 15 tracks of 849,960 bytes), was a rather large disk. That time has long since passed. However, most S/390 and zSeries installations continue to use the venerable Model 3 as their basic storage system. Most zSeries Linux systems, therefore, inherit the Model 3. At sites running z/VM, they’ll usually get minidisks carved out of this for their use rather than entire dedicated devices. Because the Linux DASD driver uses, by default, a 4K block size, the formatted capacity of a 3390-3, in a form useful to Linux, is generally about 2.3GB…

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Mainframe managers today are struggling to craft a cost-effective strategy for business continuance, of which traditional disaster recovery is only one part. The broader mandate of business continuance, however, makes it a more complicated and potentially more expensive task than mainframe disaster recovery. This is forcing managers to explore a growing set of options, especially asynchronous replication, and to assemble the optimum mix of technologies to achieve the organization’s business continuance and disaster recovery goals in the most cost-effective way…

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High-Impact ISPF Settings

This article explains several high-impact z/OS ISPF settings that you can change at the individual user level. We’ll focus on settings that apply globally (sessionwide) at the individual user level. Every ISPF user on a z/OS machine can have different values for the settings we’ll cover. Once these settings are established, they apply to many aspects of an individual ISPF session on all screens…

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The Case for Enterprise Extender

For many years, IBM front-end processors (3705, 3725 and 3745) have been at the heart of most Wide Area Networks (WANs). However, time is running out for this aging survivor from the days when networks were SNA from the desktop to the data center. IBM announced its withdrawal from marketing in 2002, and indicated support would be withdrawn in 2007. This fact alone should be enough to ensure organizations worldwide have developed and agreed upon a strategy to remove their dependencies on the 3745. Indeed, some organizations do have such a strategy and have largely executed it, while others have gone through some measure of 3745 consolidation. This usually means the remaining 3745s are located in the data center, which simply increases the impact of a 3745 failure and does nothing to remove the dependency. Unfortunately, there are others who have, thus far, taken a wait-and-see approach, maybe arguing that IBM withdrew support for 3725 years before the last 3725 was taken out of production; therefore, there’s no rush to remove the 3745. After all, they may be trying to justify that it’s fully depreciated, it works and if it isn’t broke, don’t fix it. Well, this line of thinking is very wrong…

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FlashCopy is an IBM microcode-based technology that comes as an add-on feature to the more advanced IBM DASD subsystems. Other DASD manufacturers typically have similar capabilities under different names. This technology lets the DASD subsystem handle some of the data movement task rather than relying on the operating system or programs. FlashCopy is a useful utility for backing up databases and moving large volumes of data quickly at a DASD volume level. FlashCopy Version 2 introduces data set level copy…

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