Getting disk into the backup process; adding benefits of disk while supporting existing processes - Storage Networking

As the new serial ATA disk technology begins to be integrated into backup, end users and integrators are beginning to face a new set of challenges. The issues they face include integrating the new system into enterprise backup, creating and managing the path to tape, and getting optimal performance out of the system. There are effective answers to all three, but the experience is again showing IT managers why it takes effective managed-system design to solve complex storage problems and not just new components.

Integrating Disk Into Enterprise Backup

The first major challenge to implementing a disk backup strategy is integrating it into an existing environment. Enterprise backup is complex, heterogeneous, and can touch all of an enterprise's data in hundreds or thousands of separate jobs each night. Moreover, backup isn't limited to copying and recovering files. It also organizes data sets based on what the data pool looked like at many different points in time. It keeps track of different versions. And it manages the rotation and use of media for long-term disaster recovery and data retention compliance. With this kind of scale, users can't simply insert disk resources into the process without re-architecting procedures and using different versions of backup software.

The easiest way to let enterprise backup take advantage of the performance and fault tolerance of disk is to make a disk-based system look like tape to backup applications. The technology to do that--virtual tape technology--has not been generally available for open systems backup. When ADIC created its Pathlight VX disk-to-tape system, we developed a variation of virtual tape technology built specifically to support open systems backup and we embedded it in a local controller. The system it creates provides a layer of disk-based storage with its performance and fault tolerance gains, but allows it to fit directly into an existing backup system designed around tape without requiring that a user change applications or basic processes (Figure 1). The process that is supported includes a path to real tape creation.

The Path to Tape

For long-term storage, for removability, for disaster recovery, and for compliance with data retention regulations, a removable medium like tape remains an essential part of most organizations' comprehensive data protection systems. So before any disk-based storage is made part of a backup system, two key questions need to be asked: How will data get to tape? And what kind of format and management support will it have?

How Data Gets to Tape

For the first question--how data will get to tape--there are two basic answers (see Figure 2). The fist architecture writes data to disk once, and then uses a second, on-line process to move the data to tape. The second architecture embeds the movement to tape, creating removable media off-line, in the background, and over isolated connections.