Sun’s Volume Manager

Peter Baer Galvin

It used to be Solstice DiskSuite and Solaris Disk Suite. Now it’s Solaris Volume Manager. Was the name changed to highlight new functionality, or to protect the guilty? This month, the Solaris Corner takes it for a spin to determine which is the case.

Overview

As with the past couple of Solaris Companion columns, this one addresses a new Solaris 9 feature. This month, I’ll examine Solaris Volume Manager (SVM) and take a close look at its features, problems, and a field trial. Does SVM give Veritas Volume Manager some competition on large disk-space machines? Probably not. But it does have sufficient utility to be used on small systems, as did DiskSuite, and even on mid-sized machines with moderate disk space. In the remainder of this column, I’ll look at the features and functions of SVM, walk through an implementation, and evaluate the final results.

Features

SVM is now a full member of the Solaris product. It is installed by default, not separately. Its integration is a welcome relief to those who need volume management. In the old days (Solaris 8 and below), any disk management had to be removed from any system disks before upgrades could be performed, and had to be re-implemented after the upgrade. With SVM, upgrades are supposed to be knowledgeable of it and not require it to get special treatment.

Other important changes to SVM were long in coming, but are still welcome. It now has a concept of virtual disks, in which it dices a physical disk into N virtual disks (which are variously called “volumes” and “metadevices”). “N” can be 8192 at the extreme, but it is limited by default to 128. SVM used to be limited to the standard eight partitions. A volume can be “sliced” to contain its own virtual partitions.