Compaq ProLiant 3000 SMART-2DH Array Controller Reference Guide - Page 139
Table D-1, RAID Level Characteristics, No Fault Tolerance
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D-6 Understanding Drive Arrays Table D-1 RAID Level Characteristics Distributed Data Guarding (RAID 5) Data Guarding (RAID 4) Mirroring (RAID 1) No Fault Tolerance (RAID 0) Usable Disk Space* 67% to 93% 67% to 93% 50% 100% Disk Space Formula (n-1)/n (n-1)/n n/2 n (n = no. of drives) Parity and Parity distributed Dedicated parity drive Duplicate data None Data Redundancy over each drive Minimum Number 3 3 2 1 of Drives Comments Tolerant of single drive failures. Higher performance than RAID 4. Uses the least amount of storage capacity for fault tolerance. Tolerant of single drive failures. Like RAID 5, uses the least amount of storage capacity for fault tolerance. Tolerant of multiple, simultaneous drive failures. Higher performance than RAID 4 or 5. Uses the most storage capacity for fault tolerance. Requires an even number of drives. Best performance, but data is lost if any drive in the logical drive fails. Uses no storage space for fault tolerance. * All drives are the same capacity If you require a fault-tolerant system for critical data, Compaq recommends using RAID 5 for maximum storage space efficiency or RAID 1 if I/O performance is more important. If you will be storing non-critical data and space and performance are both important, RAID 0 offers the best of both parameters. However, RAID 0 has no data protection and you will have to rely on backups in case of hardware failure. Writer: Pamela King Project: SMART-2DH Array Controller Reference Guide Comments: 295469-002 File Name: K-APPD.DOC Last Saved On: 2/27/98 12:06 PM COMPAQ CONFIDENTIAL - NEED TO KNOW REQUIRED