User manual

SuperTrak SX6000™ User Manual Appendix C
Technology Background
Introduction to RAID
RAID (Redundant Array of Independent Disks) allows multiple hard drives to be
combined together to form one large logical drive or “array.” As far as the operating
system is concerned, the array represents a single storage device, and treats it as
such. The RAID software and/or controller handles all of the individual drives on its
own. The benefits of a RAID can include: higher data transfer rates for increased server
performance, increased overall storage capacity for a single drive designation (such as,
C, D, E, etc.), data redundancy/fault tolerance for ensuring continuous system operation
in the event of a hard drive failure.
Different types of arrays use different organizational models and have varying benefits.
The following outline breaks down the properties for each type of RAID array:
RAID 0 – Striping
When a disk array is striped, the read and write blocks of data are interleaved between
the sectors of multiple drives (see Figure 15). Performance is increased, since the
workload is balanced between drives (or "members") that form the array. Identical
drives are recommended for performance as well as data storage efficiency. The disk
array's data capacity is equal to the number of drive members multiplied by the smallest
array member's capacity.
For example, one 10GB and three 20GB drives will form a 40GB (4 x 10GB) disk array
instead of 70GB. The stripe block size value can be set logically from 4KB, 8KB, 16KB,
32KB, or 64KB [Default]. This selection will directly affect performance. Larger block
sizes are better for random disk access (like email, POS, or web servers), while smaller
sizes are better for sequential access.
Figure 15 Raid 0 Striping Interleaves Data Across Multiple Drives
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