This might help...
** I was wondering the same thing a while ago and found this. Maybe it will help you out!
Info came from Wikipedia
Concatenation (JBOD)
Although a concatenation of disks (also called JBOD, or "Just a Bunch of Disks") is not one of the numbered RAID levels, it is a popular method for combining multiple physical disk drives into a single virtual one. As the name implies, disks are merely concatenated together, end to beginning, so they appear to be a single large disk.
In this sense, concatenation is akin to the reverse of partitioning. Whereas partitioning takes one physical drive and creates two or more logical drives, JBOD uses two or more physical drives to create one logical drive.
In that it consists of an Array of Independent Disks (no redundancy), it can be thought of as a distant relation to RAID. JBOD is sometimes used to turn several odd-sized drives into one useful drive. Therefore, JBOD could use a 3 GB, 15 GB, 5.5 GB, and 12 GB drive to combine into a logical drive at 35.5 GB, which is often more useful than the individual drives separately.
JBOD is similar to the widely used Logical Volume Manager (LVM) and Logical Storage Manager (LSM) in UNIX and UNIX-based operating systems (OS). JBOD is useful for OSs which do not support LVM/LSM (like MS-Windows, although Windows 2003 Server, Windows XP Pro, and Windows 2000 support software JBOD, known as spanning dynamic disks). The difference between JBOD and LVM/LSM is that the address remapping between the logical address of the concatenated device and the physical address of the disc is done by the RAID hardware instead of the OS kernel as it is LVM/LSM.
One advantage JBOD has over RAID 0 is in the case of drive failure. Whereas in RAID 0, failure of a single drive will usually result in the loss of all data in the array, in a JBOD array only the data on the affected drive is lost, and the data on surviving drives will remain readable. However, JBOD does not carry the performance benefits which are associated with RAID 0.
Note: Some Raid cards (Ex. 3ware) use JBOD to refer to configuring drives without raid features including concatenation. Each drive shows up separately in the OS.
Note: Many Linux distributions refer to JBOD as "linear mode" or "append mode." The Mac OS 10.4 implementation - called a "Concatenated Disk Set" - does NOT leave the user with any usable data on the remaining drives if one drive fails in a "Concatenated Disk Set," although the disks do have the write performance documented in the illustration above.