Exploring backup alternatives in a SAN environment (page 1 of 2)

However there are many factors that can impact the suitability of a SAN backup architecture in your environment, such as the technology requirements and the type of data that you intend to backup.

The industry trend towards consolidation and re-centralisation of storage has provoked changes in backup traditional architectures. We have seen enterprises move away from large-scale network backup solutions towards a far more consolidated model.

More recently, network-attached storage appliances have resulted in new backup methodologies. Additionally increased deployment and visibility of SAN environments has led to further developing of backup architectures.

This article looks at some of the newer backup technologies that address the growing presence of the Storage Area Network, and investigates how this new architecture can be exploited to deliver better backup performance and more cost effective manageability.

Backup Architectures
The wide varieties of environments requiring backup services and the numerous storage connectivity alternatives have resulted in several distinct backup architectures. These backup architectures have evolved with the changes in enterprise backup and recovery requirements and the availability of more sophisticated hardware and software infrastructure components.

Many of these backup architectures are applicable in a SAN environment with the availability of technologies such as IP over Fibre. In order to understand what best fits SAN environments in particular, it is worthwhile to first complete a very brief survey of the various backup architectures that exist, and to define terminology.

Local backup is the most common and straightforward mechanism for providing protection of data. Using this technique involves copying data objects (files, volumes, databases) from primary disk to secondary storage, most commonly tape media.

A local and wide area network backup architecture is an obvious alternative to the local backup architecture, and typically involves a client-server relationship.

The backup client (agent) produces a backup image from disk and sends the image across a network to the backup server, which directs this image to secondary storage.

Network Controlled Local Backup is an effective blend of the local and network backup techniques providing network controlled local backups. In this configuration the master server provides centralised administration and the media server provides local backup for itself and possibly network backup for other clients on the LAN or WAN.

The Network Data Management Protocol provides a means to perform backup of servers and appliances that are typically unable to host native backup clients or agents. NDMP backup architectures are used predominantly in environments where appliances and specialised fileservers are part of a larger enterprise backup environment.

Shared Tape Backup gives you the ability to share secondary storage devices between multiple hosts requiring backup protection. Typically fibre channel SAN's are use as the enabling technology for this type of solution.

Second-host backup is a technique designed to use shared disk environments to offload backup operations from an application server to a dedicated backup server.

Third-party copy backup techniques provide essentially the same functionality as second-host backup, the disadvantages of the third-party copy backup techniques include the evolving nature of the XCOPY specification is the loss of common platform functionality and resulting increase in management complexity.

SAN Backup Supporting Technologies and Requirements
Of the techniques discussed the two methods that offer the most significant benefits in a SAN environment are second-host backup and third-party copy.