Disk spanning – American Megatrends MegaRAID Express 500 User Manual

Page 24

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MegaRAID Express 500 Hardware Guide

10

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 400 MB disk drives can be combined to appear to the operating
system as one single 1600 MB drive.

Spanning alone does not provide reliability or performance enhancements.
Spanned logical drives must have the same stripe size and must be contiguous. In
the following graphic, RAID 1 array is turned into a RAID 10 array.

Spanning for RAID 10, RAID 30, or RAID 50

Level

Description

10

Configure RAID 10 by spanning two contiguous RAID 1 logical drives.
The RAID 1 logical drives must have the same stripe size.

30

Configure RAID 30 by spanning two contiguous RAID 3 logical drives.
The RAID 3 logical drives must have the same stripe size.

50

Configure RAID 50 by spanning two contiguous RAID 5 logical drives.
The RAID 5 logical drives must have the same stripe size.

Note:

Spanning two contiguous RAID 0 logical drives does not produce a new
RAID level or add fault tolerance. It does increase the size of the logical
volume and improves performance by doubling the number of spindles.

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