Sunday, July 4, 2010

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What Is JBOD In RAID Concept

One way to create a large storage subsystem is to not use RAID at all. Such systems often go by the moniker of "just a bunch of disks," or JBOD.

JBOD is the way we used to do things back in the olden days, when normal systems maintenance included loading coal into the machine hopper and adjusting the processor drive belts. To create a JBOD storage subsystem, you take a bunch of disks and attach them to your system, usually via one or more SCSI controllers. Individual drives may have some smarts, including an on-drive cache, but there is little other hardware support for your storage subsystem.

Drive management in a JBOD environment occurs at the system level. You use conventional tools to format, partition, and mount the physical drives. Users then take advantage of the file systems you've mounted. 
For any sort of realistic performance management, users, especially database administrators, will need to know exactly where every file system is created and mounted, so that they don't create applications that saturate one drive or SCSI controller.
For large installations, JBOD is simply not an option. If you work in a small shop on a shoestring budget, however, JBOD can help meet some of your disk storage needs. In these cases, you'll be relying on your applications and databases to provide redundancy and recovery tools, along with robust backups to help you through serious drive failures.

The one advantage of a JBOD installation is that it forces you to become intimately familiar with your drives, controllers, and disk performance. Once you have fully grasped the inner workings of disk storage, a later transition to a more sophisticated RAID subsystem will be much easier, since you will understand how to balance loads across multiple controllers, detect disk hot spots, and recognize application usage patterns among your disk drives. 

In addition, a JBOD architecture is the basis on which software RAID solutions are constructed. Learning how to make JBOD work effectively will help you make a software-based RAID configuration work better as well.

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Haja Peer Mohamed H, Software Engineer by profession, Author, Founder and CEO of "bench3" you can connect with me on Twitter , Facebook and also onGoogle+

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