LSI SAS2 manual Integrated Striping Description, Integrated Striping Example

Chapter 4: Overview of Integrated Striping Integrated Striping Description SAS2 Integrated RAID Solution User Guide

4.3Integrated Striping Description

On Integrated Striping volumes, the firmware writes data across multiple disks instead of onto one disk. It does this by partitioning each disk’s storage space into 64-KB stripes. The firmware interleaves the stripes round-robin so that the combined storage space consists alternately of stripes from each disk.

The following figure shows an example of integrated striping: the firmware writes segment 1 to disk 1, segment 2 to disk 2, segment 3 to disk 3, and so on. When the firmware reaches the end of the disk list, it continues writing data at the next available segment of disk 1.

LSI SAS2

Controller

SAS

Disk 1	Disk 2	Disk 3	Disk 4
Segment 1	Segment 2	Segment 3	Segment 4
Segment 5	Segment 6	Segment 7	Segment 8
Segment 9	Segment 10	Segment 11	Segment 12

3_00010-00

Figure 8: Integrated Striping Example

The following figure shows a logical view and a physical view of an Integrated Striping volume with three disks.

Logical View		Physical View
Stripe 1	Stripe 1	Stripe 2	Stripe 3
Stripe 2	Stripe 4	Stripe 5	Stripe 6
Stripe 3	+	Stripe 8	+
	Stripe 7		Stripe 9
Stripe N	Stripe N-2	Stripe N-1	Stripe N
			3_00011-00

Figure 9: Integrated Striping – Logical and Physical Views

Speed is the primary advantage of the Integrated Striping solution because it transfers data to or from multiple disks simultaneously. However, there is no data redundancy. Back the data up on other media to avoid losing unsaved data if one disk fails.

Page 24 LSI Corporation Confidential August 2010