Administrative Procedures for RHEL High Availability Clusters - Preparing a dasd Storage Device for Use by a Cluster of IBM z Systems Members

Updated

Contents

Overview

Applicable Environments

  • Red Hat Enterprise Linux (RHEL) 7 with the High Availability Add-On
  • IBM z Systems z/VM LPARs as cluster members

Useful References and Guides

Introduction

This procedure details how to prepare a storage device to be used by a RHEL High Availability cluster.

Procedure: Configure Shared Storage for a Cluster

Task: In z/VM enter an MDISK in the user directory

As a privileged z/VM user, modify the user directory to add a MDISK entry to one of the images that serves as a cluster member. For example, in the user directory entry for our node NODE1:

USER NODE1 PASSWRD1 2G 2G G
  ...
  MDISK 0199 3390 00001 50075 CLU01A MW

Task: In z/VM add LINK entry to user directory

Include a LINK statement in the z/VM user directory entry of the other images that serve as cluster members, to provide them shared access to the disk entry created already. For example, linking the same 0199 disk from the previous example to our node NODE2:

USER NODE2 PASSWRD2 2G 2G G
  ...
  LINK NODE1 0199 0199 MW

Task: From RHEL, configure dasd device:

On all of the nodes in cluster, add this entry for this disk to the /etc/dasd.conf file, using the ID that was included in the MDISK and LINK entries. For example, using the 0199 ID from the previous examples:

0.0.0199

Task: Format the disk

To prepare the disk, it will need to be low-level formatted and then partitioned, even if the entire disk will be used. Run the dasdfmt command to format the disk.

For example, if the previously configured device is /dev/dasdc: 

# dasdfmt -b 4096 -y -f /dev/dasdc

Then partition it with fdasd. For example, to create a partition /dev/dasdc1 that occupies the entire device just formatted:

# fdasd -a /dev/dasdc

This device is now ready to be managed and used by the cluster.

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