Snapshot software represents an image of the data as it appeared at the time the copy was initiated and creates a usable copy of it. The interval between snapshots determines the level of granularity for restore; the smaller the interval, the fewer changes to the data.
By creating a snapshot copy of the data, a file-level backup to disk or tape can be accomplished outside of the backup window, minimizing the impact on the production environment. This is the concept behind VMware Consolidated Backup (VCB) in server virtualization environments and Volume Shadow Copy Service (VSS) in Microsoft Windows environments. Snapshots also enable the capture of open files in active systems, such as messaging systems, databases and running virtual machines.
Research from the Enterprise Strategy Group (ESG) has found that snapshots are the most widely implemented advanced technology for backup. Fifty-one percent of survey respondents -- SMBs, as well as enterprise organizations -- employ snapshot solutions. Further, 26% of all respondents have plans to deploy this technology in the next 12 months to 24 months, with varying degrees of urgency in the SMB and enterprise camps.
Continuous data protection
Continuous data protection is similar to snapshot technology in that it maintains a record of data at a specific point in time. The difference is that it continuously captures changes made to data. This results in unlimited restore points, which in turn results in near-zero data loss and greater granularity in recovery. When recovery is needed, any previous consistency point can be selected.
Continuous data protection technology isn't new, but its integration with backup platforms is a more current development. A few backup vendors have embedded policy options for snapshots at specific intervals, providing built-in, near-CDP functionality. However, other vendors have gone a step further and enabled centralized control and integration between former standalone "true" continuous data protection solutions and the backup platform.
The technology addresses many of the aforementioned optimization challenges, including aggressive recovery point objectives (RPOs) and recovery time objectives (RTOs), and improved reliability of active system backup. Also, CDP delivered via the backup platform also provides the advantage of protecting heterogeneous storage devices, topologies, platforms and applications. The only drawback is that CDP may consume more storage capacity than snapshots.
ESG research examined the adoption of continuous data protection and found that 53% of respondents will deploy or plan to deploy the technology within 24 months. Two of the primary reasons cited for not using CDP are the cost of a new solution and no perceived need for the technology. Other reasons include not being familiar with the technology and a lack of skills for implementing and managing continuous data protection.
An increasing reliance on disk and the rising volume of data to be protected are two developments that make data deduplication so enticing, mainly because the disk backup process improves with deduplication. The technology's ability to eliminate redundancy in secondary storage processes optimizes network and storage resources.
By capturing, transferring and storing less data in the backup process, organizations can back up more data to disk -- retaining data on disk for longer periods of time or enabling disk-to-disk backup for more sets of data than before. Reducing data capacity also aids in better network bandwidth utilization.
For remote offices and branch offices (ROBOs), reducing or eliminating the reliance on a tape backup infrastructure in favor of disk can introduce cost savings around tape media handling. Deduplicating data aids in the transfer of data between ROBOs and the data center and/or increases local storage capacity. In the data center, the impetus may be enabling recovery from disk vs. tape to meet RTOs, or replicating data to a remote location to facilitate a disk-based disaster recovery strategy. And then there are the challenges created in server virtualization environments, as server virtualization increases the amount of data and files that would normally be kept on a single physical server. Backing up virtual hard disk images may impact network traffic, the backup window and storage capacity.
Early adopters have implemented deduplication more often in target storage systems -- including disk-to-disk appliances and virtual tape libraries (VTLs), mainly due to the ease of implementing the technology in existing backup environments. However, several backup applications now include data deduplication as a feature. Source-side deduplication in a backup application's client agent and/or media server offers a few advantages over target-side deduplication, including a reduction in LAN, WAN or SAN traffic, as well as the distribution of the deduplication workload across multiple nodes in the backup environment.
The data protection market continues to evolve with new products and features that enable more optimized backup and recovery. Some vendors could be left behind with this progress, as evidenced by the tape-based to disk-based backup transformation in most organizations.
Most recently, leading backup vendors have acquired or developed advanced technologies and more tightly integrated them into existing backup platforms. The integration of snapshot, continuous data protection and deduplication is amplifying the value proposition set forth by backup vendors and calling into question the need for standalone technologies. For example, the inclusion of data deduplication as a feature in popular backup products is a competitive threat to deduplication vendors. However, this should translate to improved backup options for your IT shop.
This article originally appeared in Storage magazine.
About this author: Lauren Whitehouse is an analyst with Enterprise Strategy Group and covers data protection technologies. Lauren is a 20-plus-year veteran in the software industry, formerly serving in marketing and software development roles.
This was first published in July 2009