Sun Microsystems 440 manual RAID 0 Disk Striping, RAID 1 Disk Mirroring

RAID 0: Disk Striping

Disk striping (RAID 0) is a technique for increasing system throughput by using several hard drives in parallel. Whereas in non-striped disks the operating system writes a single block to a single disk, in a striped arrangement, each block is divided and portions of the data are written to different disks simultaneously.

FIGURE 3-2Graphical Representation of Disk Striping

System performance using RAID 0 will be better than using RAID 1 or 5, but the possibility of data loss is greater because there is no way to retrieve or reconstruct data stored on a failed hard drive.

RAID 1: Disk Mirroring

Disk mirroring (RAID 1) is a technique that uses data redundancy—two complete copies of all data stored on two separate disks—to protect against loss of data due to disk failure. One logical volume is duplicated on two separate disks.

FIGURE 3-3Graphical Representation of Disk Mirroring

Whenever the operating system needs to write to a mirrored volume, both disks are updated. The disks are maintained at all times with exactly the same information. When the operating system needs to read from the mirrored volume, it reads from whichever disk is more readily accessible at the moment, which can result in enhanced performance for read operations.

Chapter 3 Managing Disk Volumes 55