Dell Compellent SC8000 Controller - Manual (Page 6)

Optimizing an Oracle Database with Dell Compellent Automated Tiered Storage
Page 3
Introduction
Today’s storage devices come in many choices ranging from high performance and high cost storage
devices such as the flash memory-based Solid State Drives (SSD), to slower performance and less
expensive storage devices like the mechanical hard disk drives (HDD). While it would be ideal to store
all data in the high speed devices, it would be unnecessary and impractical given the different
categories of data, the high cost of the fast disk drives, and the exploded data growth.
 Majority of enterprise data is less transactional and not frequently accessed. Transactional or
frequently changed data represents only a small percentage of the entire data storage. It is
cost effective to store only the frequently accessed data in the high performance storage
devices.
 Pricing for the high performance storage devices such as SSDs is still higher than HDDs for
comparable storage capacity. It may be impractical to store all data on SSDs for many
customers.
 The exponential data growth rate leads to the huge storage capacity requirement. As a result,
companies need to seek new ways to store data more efficiently and more cost effectively to
control the total storage cost. Storing all data in a single type of storage media cannot meet
the goal of reducing storage cost while preserving application performance at the same time.
The above factors lead to the increasing adoption of the tiered storage architecture (Figure 1).
Figure 1. Architecture of the tiered storage infrastructure
A tiered storage environment consists of two or more types of storage media with the fast and more
expensive disk devices forming the top tiers, and slower performance and lower cost storage devices
forming the lower tiers. Tiered storage aligns different categories of data to different storage tiers.
For example, mission-critical or frequently accessed data might be stored on the high performing SSD
drives in tier 1 or the SAS drives in tier 2; infrequently used data might be stored to the slower and less