JBOD (just a bunch of disks or just a bunch of drives)

Contributor(s): Brien Posey, Paul Rowlands

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.

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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

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Is there ever a good reason to use JBOD?
This is the most commonly used 'array' in home computers with multiple hard drives, and in external drives supplied for them. It is suitable for home usage because of 'non-intensive' usage [it really it is in relative terms], although it wouldn't be for a writer, for storage of financial records or of other critical data unless this were only one of multiple backups (for paranoid people like me, and people who combine 'home' and work It is absolutely not appropriate for any business usage.
There are 2 advantages
- Full space utilization
Unlike many Raid configurations JBOD does not limit to the size of the smallest disk with the array, a JBOD configuration will allow for the combined space of all the drives to be used by the end Operating System.
- Cost effective
Basic SATA disks and controllers are cheap in comparison to their SCSI, SAS and Hardware RAID cousins
Yes, now there are hyper-convergence environments that fits exactly the purpose of using JBOD.
Just a quick question: If I have a bunch of drives with files on them and put them in a JBOD enclosure. Will I lose all of the information on them?
Eventually, you will. When you consider the lifespan of human beings, which can be 15-95 years, a JBOD user of the near future will definitely lose almost everything they store to HD. The advantage of a JBOD, or 'loose' user, is that they spend (in 2009 dollars) about $150-$400 for their assortment of disks, where banks, writers, and architecture firms will need to spend $700-$3000 plus yearly upgrades and replacement media of $400-2500. My estimates are very loose; a bank will have multiple branches and ATMs, and will spend a *lot* on storage, and most likely employ a data maintenance firm.
Then why Microsoft is recommending using JBOD in their preferred architecture of deploying Exchange server 2016  and I'm quoting
Each server houses a single RAID1 disk pair for the operating system, Exchange binaries, protocol/client logs, and transport database. The rest of the storage is configured as JBOD, using large capacity 7.2K RPM serially attached SCSI (SAS) disks (while SATA disks are also available, the SAS equivalent provides better IO and a lower annualized failure rate)"
Can someone explain this to me
I'm not sure to be honest, but if I had to make a technical guess. Looking at the full picture of the recommended Exchange Deployment.. With the use of DAG and CAS arrays, you kind of have a virtual raid in that if 1 server fails.. no big deal your data should be mirrored elsewhere with a minimal hickup.

The people who are replying here do not understand the true concept of JBOD.  They think it's literally having a bunch of unmanaged disks.  In this context the JBOD is MANAGED which means it can have fault protection.

With JBOD, if 10 disks are treated as 1 big drive... what happens when 1 of the drives die?  Can it be replaced, with a minor data loss... or is everything on all 10 disks lost?

I understand how storage devices (discs) are connected within JBOD/barebone through backplanes/power distributors/expanders/HBAs.
Looking from the enclosure perspective...
- Is a JBOD enclosure, a computer/server, which I can install a generic (but compatible) OS?
- If not, is its CPU/mainboard, a special(-purpose) hardware having its own OS-like software?
- What is barebone enclosure wrt JBOD enclosure?
- Is a barebone enclosure, a computer/server, which I can install a generic (but compatible) OS?
- If not, is CPU/mainboard of barebone enclosure, a special(-purpose) hardware having its own OS-like software?

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