No matter the type of disks, there are always potential problems. The disks can be too small, too slow, or too unreliable to meet the system's requirements. While disks are getting bigger, so are data storage requirements. Often a file system is needed that is bigger than a disk's capacity. Various solutions to these problems have been proposed and implemented.
One method is through the use of multiple, and sometimes
redundant, disks. In addition to supporting various cards and
controllers for hardware Redundant Array of Independent
Disks RAID systems, the base FreeBSD system
includes the vinum volume manager, a
block device driver that implements virtual disk drives and
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.
Starting with FreeBSD 5, vinum
has been rewritten in order to fit into the GEOM architecture, while retaining the
original ideas, terminology, and on-disk metadata. This
rewrite is called gvinum (for
GEOM vinum). While this chapter uses the term
vinum, any command invocations should
be performed with gvinum. The name of the
kernel module has changed from the original
vinum.ko to
geom_vinum.ko, and all device nodes
reside under /dev/gvinum instead of
/dev/vinum. As of
FreeBSD 6, the original vinum
implementation is no longer available in the code base.
All FreeBSD documents are available for download at http://ftp.FreeBSD.org/pub/FreeBSD/doc/
Questions that are not answered by the
documentation may be
sent to <[email protected]>.
Send questions about this document to <[email protected]>.