A Storage Overview; Arrays And Logical Drives; Multiple Physical Drives (D1, D2, And D3) In A System; Multiple Physical Drives (D1, D2, And D3) Configured Into One Logical Drive (L1) - HP StorageWorks 1510i - Modular Smart Array User Manual

A Storage overview

• Arrays and logical drives

• Fault-tolerance levels
• Comparison of RAID Methods
• Choosing a RAID level
Arrays and logical drives
The capacity and performance of a single physical hard drive is adequate for home users. However,
business users demand higher storage capacities, higher data transfer rates, and greater protection
against data loss when a hard drive fails.
Connecting extra physical drives to a system increases the total storage capacity
no effect on the efficiency of read/write operations. Data is still transferred to only one physical drive
at a time.
D1
Figure 15 Multiple physical drives (D1, D2, and D3) in a system
An array controller combines several physical drives into one or more virtual units called logical drives,
which have superior performance, capacity, and/or fault tolerant features than separate physical drives.
The read/write heads of all included physical drives are active simultaneously, reducing the total time
required for data transfer.
D1
Figure 16 Multiple physical drives (D1, D2, and D3) configured into one logical drive (L1)
Because the read/write heads are active simultaneously, the same amount of data is written to each drive
during any given time interval. Each unit of data is called a block, and adjacent blocks form a set of
data stripes across all physical drives in that logical drive
R/W
D2 D3
15310
R/W
L1
D2 D3
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(Figure
(Figure 17).
HP Storage Management Utility user guide
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