Chapter 21 The Vinum Volume Manager

Table of Contents
21.1 Synopsis
21.2 Disks Are Too Small
21.3 Access Bottlenecks
21.4 Data Integrity
21.5 Vinum Objects
21.6 Some Examples
21.7 Object Naming
21.8 Configuring Vinum
21.9 Using Vinum for the Root Filesystem
Originally written by Greg Lehey.

21.1 Synopsis

No matter what disks you have, there are always potential problems:

Various solutions to these problems have been proposed and implemented. One way some users safeguard themselves against such issues is through the use of multiple, and sometimes redundant, disks. In addition to supporting various cards and controllers for hardware RAID systems, the base FreeBSD system includes the Vinum Volume Manager, a block device driver that implements virtual disk drives. Vinum is a so-called Volume Manager, a virtual disk driver that addresses these three problems. Vinum provides more flexibility, performance, and reliability than traditional disk storage, and implements RAID-0, RAID-1, and RAID-5 models both individually and in combination.

This chapter provides an overview of potential problems with traditional disk storage, and an introduction to the Vinum Volume Manager.

Note: Starting with FreeBSD 5, Vinum has been rewritten in order to fit into the GEOM architecture (Chapter 19), retaining the original ideas, terminology, and on-disk metadata. This rewrite is called gvinum (for GEOM vinum). The following text usually refers to Vinum as an abstract name, regardless of the implementation variant. Any command invocations should now be done using the gvinum command, and the name of the kernel module has been changed from vinum.ko to geom_vinum.ko, and all device nodes reside under /dev/gvinum instead of /dev/vinum. As of FreeBSD 6, the old Vinum implementation is no longer available in the code base.

This, and other documents, can be downloaded from

For questions about FreeBSD, read the documentation before contacting <>.
For questions about this documentation, e-mail <>.