Solaris Volume Manager Administration Guide

Chapter 21 Best Practices for Solaris Volume Manager

This chapter provides general best practices information from a real-world storage scenario using Solaris Volume Manager. In this chapter, you will see a typical configuration, followed by an analysis, followed by a recommended (“Best Practices”) configuration to meet the same needs.

This chapter includes the following information:

Deploying Small Servers

Distributed computing environments, often need to deploy similar or identical servers at multiple locations. These environments include ISPs, geographically distributed sales offices, and telecommunication service providers. Servers in a distributed computing environment might provide some of the following services:

These small servers have several characteristics in common:

As a starting point, consider a NetraTM server with a single SCSI bus and two internal disks. This off-the-shelf configuration is a good starting point for distributed servers. Solaris Volume Manager could easily be used to mirror some or all of the slices, thus providing redundant storage to help guard against disk failure. See the following figure for an example of this small system configuration.

Figure 21–1 Small System Configuration

Diagram shows how a single system with a single SCSI controller
can mirror two disks for redundant storage.

This configuration might include mirrors for the root (/), /usr, swap, /var, and /export file systems, plus state database replicas (one per disk). As such, a failure of either side of any of the mirrors would not necessarily result in system failure. Also, up to five discrete failures could possibly be tolerated. However, the system is not sufficiently protected against disk or slice failure. A variety of potential failures could result in a complete system failure, requiring operator intervention.

While this configuration does help provide some protection against catastrophic disk failure, it exposes key possible single points of failure:

A “Best Practices” approach would be to modify the configuration by adding one more controller and one more hard drive. The resulting configuration would be far more resilient.

Using Solaris Volume Manager With Networked Storage Devices

Solaris Volume Manager works well with networked storage devices, particularly those devices that provide configurable RAID levels and flexible options. Usually, the combination of Solaris Volume Manager and such devices can result in performance and flexibility that is superior to either product alone.

Generally, do not establish Solaris Volume Manager's RAID-5 volumes on any hardware storage devices that provide redundancy (for example, RAID-1 and RAID-5 volumes). Unless you have a very unusual situation, performance suffers. Also, you will gain very little in terms of redundancy or higher availability.

Configuring underlying hardware storage devices with RAID-5 volumes, on the other hand, is very effective. Doing so provides a good foundation for Solaris Volume Manager volumes. Hardware RAID-5 provides additional redundancy for Solaris Volume Manager's RAID-1 volumes, soft partitions, or other volumes.

Note –

Do not configure similar software and hardware devices. For example, do not build software RAID-1 volumes on top of hardware RAID-1 devices. Configuring similar devices in hardware and software results in performance penalties without offsetting any gains in reliability.

Solaris Volume Manager's RAID-1 volumes that are built on underlying hardware storage devices are not RAID-1+0. Solaris Volume Manager cannot understand the underlying storage well enough to offer RAID-1+0 capabilities.

Configuring soft partitions on top of Solaris Volume Manager RAID-1 volume, built in turn on a hardware RAID-5 device, is a very flexible and resilient configuration.