Chapter10.Redundancy Over Distance with Remote Copy

Chapter 10. Redundancy Over Distance with Remote Copy

Upon completing this chapter, you will be able to

• Participate in planning meetings and discussions in your company related to disaster protection and remote copy solutions

• Describe and diagram remote copy designs, including bunker storage and remote tertiary storage

• Analyze the system performance impact of remote copy implementations, including distance

• Discuss designs of remote copy products with vendors and compare product feature capabilities

Most redundancy technologies cover component failures such as disk drive, GBIC, cable, host bus adapter (HBA), or controller failures. But component failures are not the only threat to data access, of course. Storage subsystems can also fail or suffer disasters. And major, large-scale disasters such as floods, fires, earthquakes, industrial accidents, and terrorist acts can wipe out an entire computing facility in a single cataclysmic event. When catastrophes happen, businesses could lose all or most of their data as well as their data processing capabilities. In many cases, the ability of the company to continue serving its customers depends on having copies of data available on other storage subsystems and at other, remote locations.

Backup and recovery, the topic of Chapter 13, "Network Backup: The Foundation of Storage Management," has traditionally been the technology used to recover data. However, with data access becoming increasingly important to successful business operations, many organizations cannot afford the extended downtime that unavoidably accompanies a major recovery process using backup tapes. More importantly, the chances of achieving a full recovery become smaller and smaller as the amount of data gets larger and larger.

For that reason, many companies prefer to employ data redundancy technology that provides more immediate access to data on diskon local storage as well as at remote sites. Not only is data on disk easier to access than tape, but it is also usually easier to verify that the data redundancy strategy is working as planned.

In response to these requirements, storage companies have developed remote copy technologies that make identical copies of data on secondary storage subsystems and at remote sites that are physically distanced from their primary data processing facilities. This chapter looks at this important storage application, discussing how it works and some of its implementation variables.