JBOD (just a bunch of disks)

JBOD (which stands for "just a bunch of disks") generally refers to a collection of hard disks that have not been configured to act as a redundant array of independent disks (RAID) array.

RAID arrays write data across multiple disks as a way of storing data redundantly (to achieve fault tolerance) or to stripe data across multiple disks to get better performance than any one disk could provide on its own. Typically, a RAID array will appear to the operating system as a single disk.

JBOD is an alternative to using a RAID configuration. Rather than configuring a storage array to use a RAID level, the disks within the array are either spanned or treated as independent disks. Spanning configurations use a technique called concatenation to combine the capacity of all of the disks into a single, large logical disk. Although some RAID levels also concatenate disks, numbered RAID levels generally use striping or parity while JBOD does not.

JBOD diagram

JBOD means the individual disks are presented (to a server) with no amalgamation, pooling or structure applied. The term is in widespread use, especially in the context of computers that have software volume management, such as LVM (AIX, HP-UX, Linux), DiskSuite (Solaris), ZFS (Solaris), Veritas Volume Manager (Unixes), Windows and so on.

This was last updated in September 2005

Continue Reading About JBOD (just a bunch of disks)

Dig Deeper on SAN technology and arrays