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MaxAttach NAS 6000 Administration Guide
JBOD Just a Bunch of Disks Single Disk Control
Description
JBOD is not a RAID methodology, but simply single drive control. The controller treats
each drive as a standalone disk and provides a high-performance cache.The limitations of
JBOD are volume size limited to physical disk size, decreased performance because striping
is not present for performance enhancements, and there is no recovery from a disk drive
failure.
Fault Tolerance Cost
There is no fault tolerance with JBOD and hence no associated cost.
Performance
The benefits are speed and discrete volume availability. The cache reduces the amount of
time the computer waits for a disk to get to the right place to read or write data. The
individual disk drive volumes allows for increased data security and permits easy removal of
sensitive confidential material to secure physical storage.
Array Size
JBOD is a single disk at the physical disk level. File server O/S can group single JBOD
drives into larger multi-drive volumes, but without any striping nor with any fault
tolerance.
RAID Benefits Comparison
The tables below summarize and compare the general benefits and functions of each type
of RAID configuration.
RAID Level
RAID 0
Disk Striping
RAID 1
Mirroring
RAID 2
Striping with ECC (hamming) - Synchronous-
RAID 3
Striping with dedicated parity and synchronized disks
RAID 4
Striping with dedicated parity and non synchronized disks
Chapter #11 - Appendix - Disk Array RAID Concepts
11/07/01 -- Revision 2.0.03A
Table #1 - RAID Comparison
Description
263
Chapter #11 - Appendix - Disk Array RAID Concepts
JBOD Just a Bunch of Disks Single Disk Control
I/O
Advantage
YES - Fastest
NO
NO
YES
YES
Fault
Tolerance
No
YES
YES
YES
YES
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