DEC DS-HSZ22-AA, User Manual

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Chapter 2. RAID Array Controller
EK–SMCPO–UG. A01 2–3
From the pedestal’s perspective, the controller receives the I/O requests from the
host and directs them to the devices in the pedestal. Since the controller proc-
esses all the I/O requests, it eliminates the host-based processing that is typically
associated with reading and writing data to multiple storage devices.
The controller does much more than simply manage I/O requests: it provides the
ability to combine several ordinary disk drives into a single, high-performance
storage unit called a storageset. Storagesets are implementations of RAID tech-
nology, also known as a “Redundant Array of Independent Disks”. Every storag-
eset shares one important feature: whether it uses two disk drives or 14, each
storageset looks like a single storage unit to the host.
You create storage units by combining disk drives into storagesets such as stripe-
sets, RAIDsets, and mirrorsets, or by presenting them to the host as single-disk
units (see Figure 2–2).
Figure 2–2 Units Created from Storagesets, Partitions, and Disk Drives