User`s guide

StorTrends® NAS Software (Version 2.2) User’s Guide
104
RAID Overview
RAID is a collection of specifications that describe a system for ensuring the reliability
and stability of data stored on large hard disk drive subsystems. A RAID system can be
implemented in a number of different versions (or RAID Levels). The standard RAID
levels are 0, 1, 3, and 5.
Disk Striping
Disk striping writes data across multiple hard disk drives instead of just one hard disk
drive. Disk striping involves partitioning each hard disk drive storage space into stripes
that can vary in size. These stripes are interleaved in a repeated sequential manner. The
combined storage space is composed of stripes from each drive. StorTrends NAS
Software supports stripe sizes of 8 KB to 512 KB.
For example, in a four hard disk drive system using only disk striping (as in RAID level
0), segment one is written to hard disk drive one, segment two is written to hard disk
drive two, and so on. Disk striping enhances performance because multiple hard disk
drives are accessed simultaneously; but disk striping does not provide data redundancy.
Segment One
Segment Five
Segment Nine
Segment Two
Segment Six
Segment Ten
Segment Three
Segment Seven
Segment Eleven
Segment Four
Segment Eight
Segment Twelve
Hard Disk Drive
One
Hard Disk Drive
Two
Hard Disk Drive
Three
Hard Disk Drive
Four
Terminology Description
Stripe Width Stripe width is the number of hard disk drives involved in a volume
where striping is implemented. For example, a four hard disk drive
volume with disk striping has a stripe width of four.
Stripe Size The stripe size is the length of the interleaved data segments that are
written across multiple hard disk drives.