Raid 5; Spare Drive - Promise Technology SMARTSTOR NS4300N User Manual

RAID 5

High Read data transaction rate
Medium Write data transaction rate
Good aggregate transfer rate
Most versatile RAID level
Recommended applications for RAID 5:
• File and Application servers
• WWW, E-mail, and News servers
• Intranet servers
RAID 10
Implemented as a mirrored RAID
Volume whose segments are RAID 0
RAID Volumes
High I/O rates are achieved thanks to
multiple stripe segments
Recommended applications for RAID 10:
• Imaging applications
• Database servers
• General fileserver

Spare Drive

A spare is a disk drive that has been designated to replace a failed disk drive in a
RAID Volume. In the event of the failure of a disk drive within a RAID 1 or three-
drive RAID 5 Volume, the spare drive is activated as a member of the RAID
Volume to replace a disk drive that has failed.
A spare drive cannot replace the failed drive in a RAID 0 Volume because of the
way in which data is written to the disk drives under RAID 0.
A spare drive is not available for a RAID 10 Volume because RAID 10 requires all
four disk drives in the SmartStor enclosure. However, when you replace the
failed disk drive, the SmartStor will automatically rebuild the RAID Volume using
the new disk drive.
Advantages
Advantages
Chapter 7: Technology Background
Disadvantages
Disk failure has a medium impact on
throughput
Disadvantages
Very high disk overhead – uses only
50% of total capacity
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