Configuring Boot Disks With Solaris Volume Manager Software
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This article is a practical guide for system disk configuration. It describes how to partition the system disk, mirror it, and create and maintain a contingency boot disk.
We attempt to cover a wide range of availability requirements by presenting two-, three-, and four-disk configurations. Every additional disk adds protection. The idea is to select one configuration, based on the cost/benefit ratio in a given situation, then use the corresponding runbook as a guide for implementation. The SUNBEsdm package is also provided with scripts for a fully automatic implementation.
In this document, we follow the concepts of the Sun BluePrints_ book "Boot Disk Management—A Guide for the Solaris_ Operating Environment" by John S. Howard and David Deeths. We add an explicit comparison of the use of Solaris_ Volume Manager software and VERITAS Volume Manager (VxVM) software for mirroring the system disk.
This article is an update to "Configuring Boot Disks With Solstice DiskSuite_ Software" by Erik Vanden Meersch and Kristien Hens (Part #816-4526-10). The basis for the current text is the Solaris 9 Operating Environment, Solaris Volume Manager software, and VxVM 3.2 software.
This Sun BluePrints OnLine article covers the following topics:
Hardware configuration
System disk partitioning
Two-disk configuration
Three-disk configuration
Four-disk configuration
Comparison of Solaris Volume Manager software and VxVM software
Runbook for creating the Solaris Volume Manager software state database
Runbook for a two-disk configuration
Runbook for a three-disk configuration
Runbook for a four-disk configuration
Uses of SUNBEsdm scripts
Introduction
System disks can be protected two ways: disk mirroring and file system backup. These two methods are complementary and cover different types of failure. Disk mirroring keeps the system running when a disk stops responding to commands. Backup provides a recovery path when files (or entire file systems) are removed or corrupted.
Sun Microsystems supports two volume managers for mirroring system disks: VERITAS Volume Manager (VxVM) software and Solaris Volume Manager software. VxVM software is widely used on servers with a large number of disks and logical volumes and can be considered a de facto standard.
We advocate using Solaris Volume Manager software for mirroring the system disk, even when VxVM software is chosen for volume management of application data. This choice is not obvious at first sight because both Solaris Volume Manager software and VxVM software work perfectly under predictable circumstances. The difference becomes apparent in case of disaster (defined in this context as a situation where, due to some problem, the system no longer boots).
It is not the intention of this document to provide an absolute best practice for system disk configuration. Instead, our goal is to:
Present the arguments in favor of using Solaris Volume Manager software for the system disk. These arguments are familiar to many people, who often learned them the hard way, but we have not found them to be formally documented.
Make life easier for the Solaris Volume Manager software user by providing runbooks with the commands detailed and the correct sequences provided. An engineer who routinely installs systems may not need this information, but we believe that there is a large audience who can benefit from some assistance in this area. We assume some level of Solaris Operating Environment and Solaris Volume Manager software knowledge.
Provide the scripts for fully automatic implementation. The scripts essentially execute runbooks.
Runbooks and scripts are based on system disk partitioning in /, /var, and swap. This partitioning is widely accepted as a good practice. Because a carelessly partitioned system disk may cause considerable trouble, we dedicate a separate section in this article to discussing the rationale of the /, /var, and swap partitioning.