LSI MegaRAID SCSI 320-2 RAID Controller Series 518 - Manual (Page 31)

RAID Overview 2-7
Copyright © 2002 by LSI Logic Corporation. All rights reserved.
2.3.7 Disk Spanning
Disk spanning allows multiple disk drives to function like one big drive.
Spanning overcomes lack of disk space and simplifies storage
management by combining existing resources or adding relatively
inexpensive resources. For example, four 60 Gbyte disk drives can be
combined to appear to the operating system as one single 240 Gbyte
drive.
Disk spanning alone does not provide reliability or performance
enhancements. Spanned logical drives must have the same stripe size
and must be contiguous. In
Figure 2.3 , two RAID 1 arrays are turned into
a RAID 10 array.
Figure 2.3 Disk Spanning
The controller supports a span depth of eight. This means that eight
RAID 1, 3, or 5 arrays can be spanned to create one logical drive.
RAID 1
Disk 2
Data Flow
Disk 1 Disk 4 Disk 3
RAID 1
RAID 0
Segment 1
Segment 3
Segment 5 Segment 1
Segment 3
Segment 5 Segment 2
Segment 4
Segment 6 Segment 2
Segment 4
Segment 6 Segment 2
Segment 4
Segment 6
MegaRAID Controller