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.
