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To tape or not to tape?

Tape was once the only option because hard disks were incredibly expensive. And since old habits die hard, many believe tape is the default standard for backup even today. But nearly unlimited disk storage space has changed the backup dynamic in ways tape can't match.

There are many ways to backup files from individual computers and servers, but most backup systems make a full backup then track the changes. If you select your My Documents folder for backup, the backup software will make a copy of all those files. When you change a file inside that folder only the sections of the file that are changed are moved to the backup system. When you need to restore a file the backup software merges the original file with the changes and sends you the latest version of the file.

Tape backup systems spread the original and incremental changes across multiple tapes, at least when you start protecting a larger amount of data than you can store on one tape. The software tracks which tapes the changed bits are on, but chasing those tapes down and getting the bits put together in the right order can be tricky. And the older a tape is, the less reliable the restoration process.

With an unlimited amount of disk storage, you bypass the scavenger hunt for the right tapes in the right order. The backup software places the original file and the incremental changes in the same backup storage pool, so all the bits are in the same place, even if they're not on the same physical hard disk. Restorations go much faster and are much more reliable. This applies whether the backup storage space lives in-house on your network, or at a backup service provider somewhere on the Internet.

There are many other reasons why companies prefer disk as the backup medium of choice. “It saves time running backups as well as during the recovery process. If you have restore a file that was accidentally deleted, it is far quicker to get it from a disk staging area than go through a tape retrieval job. Equally, I/O transfer rates to disk, especially when it’s write-intensive operations like backup, can be handled very efficiently by multi-spindle arrays. When our customers ask for advice and best practices around designing backup infrastructure, we generally propose a three-tier architecture – primary disk to staging disk to tape,” says Anthony Harrison, Senior Principal Solutions Specialist, Symantec.

Does this mean it is the end-game for tape? Far from it. Tape storage still has its supporters and admitting that while data backup is moving away from tape- or already has- say that IT decision makers, especially SMBs should not overlook possibilities and opportunities that tape still provides.

“Now more than 50 years old, magnetic tape has lived through decades of social, political, and technological revolution. Compared with today’s blisteringly fast and reliable disk technologies, it may be out of date. The reality is, far from having one foot in the grave, tape is re-inventing itself as a fast, high-capacity storage medium. Tape technology has become indispensable as the only viable and affordable means of accommodating the sheer magnitude of information that the world now needs to keep safe, sound, and out of harm’s way,” says Stefan Wolfs, Business Development Manager- Enterprise Storage, HP Middle East.

Tape has also emerged as the ideal medium for long term archival. “Mounting legislation to prevent accounting fraud, as well as new compliance regulations in financial services and other industries, have made it very clear that disk is not a viable option for maintaining vast, impregnable stores of information. And tape is the only viable solution for storing the astronomical volumes of data generated in film, broadcasting, science, and medicine,” says Wolfs.

Harrison offers another perspective: “There is a certainly still a place for tape in today’s IT environment, especially when you look at the cost of storage, as it requires no power. Equally there is definitely a place for disk for performance and service level reasons and an area of overlap in between the two where the correct analysis of recovery requirements and a recognition of the changing value of data over time will allow the correct placement of data on the most appropriate storage tier. In fact we are seeing an increasing segmentation of the primary storage area into multiple tiers based on the value and access requirements of the data.”

Tape proponents say another reason to consider the technology is the recent arrival of the LTO-5 format in tape technology. “With a native capacity of 1.5 terabytes and 3.0 terabytes of compressed storage, data transfer rates of up to 280 MB/second compressed, data encryption, and new partitioning functionality to enhance file control and space management, the LTO 5 format offers significant improvements over prior LTO tape generations. Thus tapes continue to evolve and provide one of the most reliable, cost effective and energy saving medium for storage requirements,” says Riyaz Abdulla, Regional Manager, Imation.

Wolfs agrees: “It will allow customers to keep pace with the needs of their primary data in terms of storage growth and the growing volumes of data within their existing backup window. In addition it will control the operational costs associated with tape data protection and confidently store and secure confidential customer data on tape.”

There is no universal solution that applies to every business, and when it comes to storage, organizations need to look within for the answer to what solution or format is most applicable to their case. Yet, we are willing to say that tape still has a valid place in your data centre.

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