easyRAID Q12-U4R2 Hardware User Manual

easyRAID Q12-U4R2 Hardware User Manual Manual pdf 16 page image

ERQ12-U4R2 & ERQ12-F2R2 Serial ATA Disk Array Systems71 Overview – Understanding RAIDSummary of RAID LevelsThe following table summarizes the performance characteristics of each RAID level. A highavailability or access rate number indicates high availability or quick access rate.ArrayGroup Availability AccessRateCapacityUtilization DescriptionNRAID 1 1 100% Sum of all disks in the arrayJBOD 1 1 100% Data is distributed by filling eachdisk in turn.RAID 0 1 5 100% Data is divided into pieces andwritten to all disks in parallel.RAID 1 5 2 50% Data is duplicated on both disks.RAID 3 3 3 Between 67%for 3 disks to94% for 16disksData is divided into pieces; theparity of these pieces is calcu-lated; and the pieces are writtento separate disks in parallel withthe writing of the parity to a dedi-cated disk.RAID 5 3 3.5 Between 67%for 3 disks to94% for 16disksData is divided into pieces; theparity of these pieces is calcu-lated; and the pieces and parityare written to separate disks inparallel. The parity is written to adifferent disk each time.RAID 0+1 4.5 5 50% RAID 0+1 is a RAID 1 consistingof RAID 0 members.RAID 30 4 4 Between 67%for 6 disks to88% for 16disksRAID 30 is a RAID 0 consistingof RAID 3 members.RAID 50 4 4.5 Between 67%for 6 disks to88% for 16disksRAID 50 is a RAID 0 consistingof RAID 5 members.