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 https://download.freebsd.org/ftp/doc/
Questions that are not answered by the
    documentation may be
    sent to <freebsd-questions@FreeBSD.org>.
    Send questions about this document to <freebsd-doc@FreeBSD.org>.