Tape pipeline for BC/DR planning: new considerations in backup and recovery - Storage Networking

Computer Technology Review, Jan, 2003 by Patty Barkley

Tape has long been an affordable backup medium. However, when it came to remote data replication, tape had severe limitations. With heavy latency impact over as little as a 10-mile distances, remote tape backup was not a viable option for business-continuity/disaster-recovery(BC/DR) planning--until the introduction of tape pipelining.

Tape pipelining virtually eliminates the impact of latency on the sustainable throughput of tape backup over distance. With tape pipelining, the remote tape backup system appears local to the server and is able to sustain high performance over thousands of miles. This greatly enhanced performance over distance allows considerable flexibility to companies considering tape as part of their BC/DR strategy. Tape pipelining can enable a single central site to act as a backup facility for many geographically dispersed data centers. It can also enable backup from a central site to a remote site.

Companies can backup stored tape data across low-cost and readily available IP connections, using both newer native Fibre Channel tape drives as well as older SCSI drives. In addition, open systems servers such as UNIX and NT can be incorporated into remote tape strategies.

Many companies are using IP networks for remote disk mirroring which is typically synchronous and therefore uses substantial network bandwidth during the day. Since tape backup is typically asynchronous and often done during nights and weekends, tape pipelining means that businesses can now use their existing IP networks for both disk mirroring and remote tape backup solutions.

The result is improved data protection and recoverability in the event of a disaster and a significant reduction in the total cost of ownership of a remote BC/DR solution.

With tape pipelining, a single location can act as the backup for numerous remote servers and centrally manage the backup/restore operation. Tape pipelining over IP allows this to be done over plentiful yet inexpensive IP connections.

Selecting BC/DR Solutions

In planning BC/DR systems, businesses can select from a wide range of data-protection solutions (see Figure 1). The choices they make will be determined by the importance of the information they need to protect (i.e. its time sensitivity and business, value) and the amount of money they are willing to spend to protect it. These factors help determine the appropriate recovery lime objective (RTO).

Industry research shows that a typical mid-sized to large enterprise might have 150 mission- and time-critical applications that require continuous availability; 300 or so applications that require data restoration within four to 24 hours; and 100 or so non-critical applications that can wait as long as several weeks for data restoration.

Levels of information protection: If a business cannot continue profitable operations without its data, it usually implements a remote hot site that completely duplicates critical data and applications and makes them continuously available. The cost of such a solution is justified by the cost to the business of even a few minutes of down time. At the other end of the spectrum is business data that may not need to be restored for days, weeks or even longer after a data center disruption. In fact, some business data requires no restoration at all but simply needs to be protected for legal and archival purposes.

The most cost-effective enterprise-wide BC/DR plan will probably involve a mixture of disk and tape technologies, from the most expensive for data that needs to be continuously available to less expensive technologies for data of less time sensitivity and importance. Figure 2 shows what such a plan might involve.

New factors and increased focus in BC/DR planning: BC/DR strategies are affected by the increasing amount of business data being pushed into the mission-critical category, requiring continuous availability. Businesses are also aware that the dangers to their mission-critical data are greater than ever before. Not so long ago businesses had to plan for human error, technical glitches and, of course, natural disasters. Post 9/11, businesses must also plan for terrorist attacks that, as a November 2002 report from Illuminata put it, could "take out more than just a couple of floors of one data center."

Indeed, government agencies and private disaster planners are urging businesses to establish BC/DR systems that separate primary and backup sites by at least 200 miles, instead of the typical 60 miles. The SEC and Federal Reserve are calling for businesses that play a significant role in financial markets to establish fully redundant backup sites at least 300 miles offsite and be able to recover critical activities on the same business day of a disaster.

Tape Backup Market

The evolution toward networked storage, the heightened awareness of business-continuity and disaster-recovery planning and the need to reduce costs and improve efficiencies throughout IT, is stimulating the market for cost-effective tape and enterprise backup solutions.