Application Design Issues Cause Low Throughput to Virtual Tape

Dave HeggenBy Dave Heggenlow throughput application failure

Our story begins as our stories usually do, somewhere in the middle after the customer has been working on a problem, in this case low throughput to virtual tape, for a while and they are just about to give-up.

The customer had a group of tape jobs that frequently would not finish on time. On time means the jobs complete within the batch window. Not on time means they would run beyond the batch window and would compete with the online activity. Some days the job would run in less than an hour, while the same job on other days would run for 10 to 15 hours.

Low Throughput to VSM Tape Systems

The customer investigated the issue when the jobs ran long and found that the throughput to the VSM tape systems was low for the jobs in question. A joint investigation with Oracle was started under the assumption that the problem was caused by the VSM tape systems. My intel tells me that 6 people from the customer worked on the investigation for a whole month and Oracle was unable to find anything wrong from a hardware or software perspective.

Continue reading

How to Measure the Impact of a Zero RPO Strategy

Merle SadlerBy Merle Sadler

Have you ever wondered about the impact of zero RPO on Mainframe Virtual Tape for business continuity or disaster recovery? This blog focuses on the impact of jobs using the Oracle/STK VSM Enhanced Synchronous Replication capability while delivering an RPO of 0.

A recovery point objective, or “RPO”, is defined by business continuity planning. It is the maximum targeted time period in which data might be lost from an IT service due to a major incident.

Zero RPO - Recovery Point Objective

Continue reading

Break Open Your VSM Black Box and Expose Internal Tape Processing

J._Ticic-web0By John Ticic

 

When virtual tape systems run properly, it’s great. But when there are problems, or you need to examine detailed tape information, the virtualization makes it hard to see what is really going on inside the black box.

Luckily, with z/OS we have SMF, and the virtual tape hardware vendors can define a custom record to provide measurements on the internals that can help see what is happening inside. Oracle STK VSM, for instance, generates detailed SMF data in a user record that allows us to examine tape processing in fine detail using the intelligent post-processing from the enhanced Oracle Tape support in IntelliMagic Vision.

Some of the questions that you may want answered are:

    • Why are the tape mounts taking so long?
    • How many virtual tape mounts need to be staged from real tapes?
    • Are my virtual tapes being replicated in a timely fashion?

Continue reading