Disaster recovery - saving your business (page 2 of 2)

Networked storage solutions will show a robust combined annual growth rate of 67 percent to 2003, according to IDC, while the growth rate for storage solutions based on the traditional server-with-attached-storage-array model will decrease by 3 percent during the same period.

Of course, companies rarely mothball older, still-serviceable storage components when they bring new storage components in-house. Thus, the move to NAS and SANs merely increases the number of platforms on which data is stored as well as the number of targets to which data must be restored following a disaster.

Networked storage solutions can pose special difficulties that significantly degrade the already-marginal speeds of most tape-based data-restoration solutions. For example, in a SAN, physical disk devices are increasingly "managed" by storage domain servers, storage routers and/or software-based virtualisation products that work to deliver virtual volumes to SAN-attached servers.

These provide the real value of a SAN: They enable dynamically scalable volumes comprising many distributed physical disks and array partitions that can be grown or shrunk to meet changing storage demands.

In a storage-restoration situation, these SAN virtualisation layers must also act as interpreters, or filters, that direct data streams back to the target disks and partitions that make up the virtual volume where data normally resides.

This process introduces several thorny issues related to how data-layout records are maintained, and how the records can be interpreted efficiently by the virtualisation products so that data is restored correctly and quickly.

VERITAS Software has launched initiatives to address these issues. Ironically, early adopters of SAN technology often cite efficient backup as one of their primary reasons for embracing the topology. Restoration, however, is an important limitation to SAN efficacy especially as virtualisation approaches come to the fore.