Sun Microsystems 220R manual Disk Striping RAID, Disk Striping With Parity RAID, Hot Spares

Disk Striping: RAID 0

Disk striping (sometimes called RAID 0) is a technique for increasing system throughput by using several disk 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.

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 drive.

Disk Striping With Parity: RAID 5

RAID 5 is an implementation of disk striping in which parity information is included with each disk write. The advantage of the technique is that if any one disk in a RAID 5 array fails, all the information on the failed drive can be reconstructed from the data and parity on the remaining disks.

System performance using RAID 5 will fall between that of RAID 0 and RAID 1, and all data loss is fully protected.

Hot Spares

In a hot-sparesarrangement, one or more disk drives are installed in the system but are unused during normal operation. Should one of the active drives fail, disk write operations are automatically redirected to a hot-spare disk and the failed disk drive is retired from operation.

72 Sun Enterprise 220R Server Owner’s Guide • October 1999