Rosewill RSV-S4-X user manual Introduction to RAID, Segmenting Disks

4 Bay SATA to eSATA 3.5” HDD RAID Storage System RSV-S4-X User Manual

2 INTRODUCTION TO RAID

2.1 RAID VOLUMES

RAID technology allows one or more disks to be combined into a logical volume which provides greater performance and/or protection than standard disk drives. These volumes, also known as RAID Groups, appear like regular disk drives to the operating system and can be partitioned, formatted and used just like any other normal disk. The complexity of the RAID is hidden within the driver.

There are several different methods of combining disks, each with its own advantages and disadvantages. Each method is referred to as a RAID “level” such as RAID 1, or RAID 5. The details of each level are summarized below and detailed in the following sections.

	RAID LEVEL	CONFIGURED		ADVANTAGES	DISADVANTAGES
		AS
0		Striped		Excellent performance, low cost	No data protection
1		Mirrored		Excellent data protection	High cost
10		Mirrored Striped		High performance, excellent	High cost.
				data protection.
5		Parity RAID		Good data protection, good	Some performance
				value	degradation for writes.
	Combination	Concatenated		Good performance, low cost,	No data protection
				large Volume size
	Single Drive /	Contiguous	Same as single disk		Same as single disk
	Segment

2.2SEGMENTING DISKS

For increased versatility, the SATARAID5 software allows individual disks to be divided into smaller segments which can then be combined into different volumes. As an example, if a user has one set of data that must be protected at all costs, another set of data which should be protected at reasonable cost and another set that doesn’t need any protection at all; the user can divide three disks into sections as shown in Figure 1. The yellow regions define the

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