IBM ATA 133, User Manual

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IBM ATA 133 RAID Controller User's Guide 6
Disk Spanning
Disk spanning allows multiple hard 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.
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, a pair of RAID 1 arrays are turned into a RAID 10 array.
Figure 2-3. Disk Spanning
Segment 1
Segment 3
Segment 7
Segment 1 Duplicate
Segment 3 Duplicate
Segment 7 Duplicate
Segment 2
Segment 4
Segment 8
Segment 2 Duplicate
Segment 4 Duplicate
Segment 8 Duplicate
Segment 5 Segment 5 Duplicate Segment 6 Segment 6 Duplicate
Data Flow
RAID 1 RAID 1
RAID 10
RAID 0
RAID Terminology
The following sections explains terms associated with RAID, including:
•
physical drive
•
physical drive state
•
array
•
array state
•
logical drive
•
rebuild
•
hot spare
•
consistency check
•
fault tolerance