Operating Systems

Identifying and documenting success criteria is critical. Too many projects fail because they have vague or non-existent success criteria or they didn’t determine how to measure test results. With documented, clearly measurable success criteria, you can avoid inconclusive results. Possible examples of success criteria include:

• Cost savings of software by using fewer IFLs
• Response time reduction
• Throughput measurement improvement
• Memory over-commit ratio greater than 1:1
• Network latency reduction due to virtual networking
• CPU utilization reduction.

Environment Setup

Once the project plan is completed, you can set up the POC environment. IBM, or other business partners, can help with this step and with skills transfer. There are many IBM Redbooks, cookbooks, and other documents that provide step-by-step instructions. Getting a skilled resource to help you the first time will boost your chance of success. If you go it alone, ensure you have the latest versions of these publications; there have been many changes over the last 10 years. Sending your staff to a few Linux on System z training sessions is another way to help minimize risk.

Configuration of z/VM for a Linux on System z Environment
 
Whether you’ve chosen Novell SLES or Red Hat’s RHEL as your Linux distribution, there are common z/VM installation and configuration steps to follow. Start by downloading the latest version of the Guide for Automated Installation and Service for z/VM 6.1 (see http://publibz.boulder.ibm.com/epubs/pdf/hcsk2c00.pdf). Before starting, thoroughly read this excellent reference material.

For z/VM on z10 and later hardware, the best installation approach is to use a DVD. Chapter 4 of the guide contains helpful planning worksheets with answers to common installation questions. Completing these worksheets in advance will save time. Typically, separate teams handle disk space allocation, security, networking, and other areas that need planning. For example, z/VM will require its own IP address for a 3270 session if you require the ability to log in from a workstation, so the network team will need to be involved.

Chapter 5 of the guide addresses z/VM installation. Each z/VM environment is different. This article assumes you want to install a simple z/VM system per the referenced guide. It also assumes your network is running and you can navigate a 3270 session in z/VM and z/VM commands.

Tips and Tricks

Here are some recommended changes to the SYSTEM CONFIG file:

Adding paging volume(s) to z/VM. This is a good practice. Having adequate system resources is essential. Paging volumes are just as important as central and expanded storage. z/VM will make intelligent decisions on what memory pages it can move to expanded storage and then to disk. You should also keep paging devices in z/VM uniform in size. If you allocated 3390-3s, continue to add paging devices of that size. If you mix and match devices, such as 3390-3s and 3390-9s, it can create performance issues. z/VM will page to disk in a round-robin fashion, but as the smaller 3390-3 fills up, it will drop out of the dispatcher/scheduler algorithms. Paging volumes should be spread out on different ranks, drives, and spindles to maximize parallelism.

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