Disk Based Backup Solutions:
Careful analysis of this environment identified multiple bottlenecks that could be addressed to improve the situation. Given a variety of cost and implementation process variables, it was determined that the most cost-effective option, and the measure that would also deliver the most benefit, was a D2D architecture. Secondary disk has been implemented as the initial destination for backup jobs. From that location, disk based backup solutions is subsequently cloned to tape in a process that is controlled by the backup application. A copy of disk-based backup data is maintained on disk for a period of time where it is accessible for restore operations.
The implementation of D2D required some minor modification of the disk -based backup environment, but the overall effort was not excessive. The organization experienced roughly a 60% reduction in the amount of time necessary to complete a disk-based backup and recovery solution and a noticeable decrease in the wear and tear on tape resources, as the cloning process consistently results in full streaming of the tape drives.
Vendors have taken a couple different approaches to bundling this technology and approaches to the role that it can play in the backup and recovery operation. The following items characterize tape emulation some of the differentiation in the marketplace:
Emulation versus virtualization: The terms emulation and virtualization are commonly used interchangeably, while some vendors, analysts and users have defined these as having different requirements and capabilities. For the purposes of this paper, the two will be treated as separate but complementary technologies. Tape emulation provides an interface to a disk device that causes the disk to appear as a tape resource to hosts, allowing servers to send data using native tape management and protocols.
As tape virtualization still falls into the 'emerging category, this paper will focus more on tape emulation technologies, which have made greater strides in establishing themselves as a proven mainstream solution in open systems environments. Appliance: Some tape emulation products come bundled as an appliance that includes a server, software and disk-based backup solution. This approach offers a turnkey solution to customers for simplified implementation.
Software Only: Other tape emulation products come as a software-only solution. This allows the customer to choose the optimal server architecture for its data volumes, performance needs, infrastructure, etc.; also, it allows the choice of which open systems disk based backup solutions product would best fit the environment.
Data Mover or Not: Tape emulation vendors take differing positions on whether the tape emulation technology should be a passive or active storage device. In the passive approach, the tape emulation technology allows the backup application and server to take responsibility for migrating data from disk to tape for archival purposes. In the active approach, it can manage this task with or without direction from the backup server.
The benefit of having the disk based backup solution server manage this I/O, is that seamless command and control is maintained in the environment and the risk of having data integrity challenges in the backup application is minimized. The advantage of having the tape emulation product manage this data migration is that the I/O can occur without passing through the backup application server, which allows the server to perform its other tasks without being impacted.
