Hot Spares; Raid 0: Disk Striping; Raid 5: Disk Striping With Parity - Sun Microsystems Enterprise 250 Owner's Manual

RAID 0: Disk Striping

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.
Figure 10–6
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.

RAID 5: Disk Striping With Parity

RAID Level 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 spares" arrangement, 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.
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