Understanding RAID Concepts and Levelswww.3ware.com 9Single DiskA single drive that has been configured as a unit through 3ware software.(3BM, 3DM 2, or CLI). Like disks in other RAID configurations, single diskscontain 3ware Disk Control Block (DCB) information and are seen by the OSas available units.Single drives are not fault tolerant and therefore not recommended for highavailability systems unless additional precautions are take to prevent systemhangs and data loss.JBODA JBOD is an unconfigured disk attached to your 3ware RAID controller.JBOD configuration is no longer supported in the 3ware 9000 series. AMCCrecommends that you use Single Disk as a replacement for JBOD, to takeadvantage of advanced features such as caching, OCE, and RLM.JBOD units are not fault tolerant and therefore not recommended for highavailability systems unless additional precautions are taken to prevent systemhangs and data loss.Hot SpareA single drive, available online, so that a redundant array can beautomatically rebuilt in case of drive failure.For additional information about RAID levels, see the article “RAID Primer”on the 3ware website, at:http://www.3ware.com/products/pdf/RAID_Primer.pdf.Determining What RAID Level to UseSelect the RAID configuration to use based on the applications to be used onthe system, whether performance or data protection is of primary importance,and the number of disk drives available for use.Review the information under “Understanding RAID Concepts and Levels”on page 5 to determine the type of RAID configuration most appropriate foryour needs and use the tables below to determine what RAID levels areavailable, based on your particular controller model and the number ofavailable drives.The RAID configurations available to you are determined by the number ofports on your controller, and the number of drives attached to those ports. Youcan configure all drives in one unit, or you can configure multiple units, if youhave enough drives.
