Operating Systems

This time of year, news on z/VSE is typically slow … the fall announcements have been made, digested, and discussed. However, soon, the late winter/spring announcement cycle will begin.

In a discussion with a z/VSE user just before Christmas, he indicated his company was facing the potential problem of exhausting programmer logical units (SYS numbers, example SYS000 through SYS255) in a partition. The user indicated his site had only 48 free programmer logical units in the database partition and expected to exhaust those within 18 to 36 months. The current growth rate is 16 additional devices per year.

Of course, my first thought was, “Aha, a CICS partition with a need; the solution is MRO.” However, my assumption was incorrect. This user was experiencing this problem in the partition that runs his site’s database product, not in CICS.

After careful examination, we found some SYS numbers that could be released and used for expansion. This would extend the life of the current solution by two more years and required minimal cost and disruption. This was certainly a good short-term solution, but probably not acceptable as a long-term solution.

We identified a longer-term solution: migration to larger DASD devices. For example, moving from 3390-3 devices to 3390-9 devices would effectively free 66 percent of the required SYS numbers and extend the life to 20-plus years. Of course, moving to even larger devices would provide even more growth capability. Although this solution is costly and requires down time for the data to be offloaded and reloaded, it offers the best long-term solution. Because the data is required online 24/7/365, downtime is a major issue to be avoided, if possible, so it’s best to move to the largest disk available.

Another potential solution would be to split the database over two or more partitions; however, we deemed that solution not feasible at this time, but it remains on the list.

As for extending the programmer logical units in each z/VSE partition from 256 to xxx, it’s possible, but do we have the business justification for it? We’ve currently identified only one company with this issue, but there may be more. If so, we need to know who you are, what your problem specifically is, and how the prior solutions apply. You can contact me via email at pclark@cprsystems.com.

News From z/VSE Development

Here’s an overview of some of the performance-related attention routine commands available in z/VSE 4.2. 

To display the syntax of the SIR operands, enter "SIR ?" on the z/VSE console. Some SIR monitoring functions need to be activated before data can be displayed on the console. SIR without any operand provides status information about your z/VSE system, such as the z/VSE level, CPU usage, and system counters. The SIR MON command reports Supervisor Call (SVC) statistics and system bound conditions.

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