For more than 50 years, tape has been one of the most reliable, cost-effective storage media in data processing. Currently, there are several factors contributing to a resurgence in the use and popularity of tape:
- Virtual tape is increasingly common in most data centers
- The cost per gigabyte of tape storage is falling annually
- New technology, such as Write-Once- Read-Many (WORM) and tape encryption are having an impact. Better technology also is becoming increasingly affordable:
- Tape storage cost has fallen to roughly $140 per terabyte of storage
- Transfer speed has increased to 260 Mbytes/second
- Capacity per single cartridge has increased to 500GB before compression.
So, this might be a good time to consider what tape can do for you or how to take greater advantage of it. This article discusses the role of tape, storage industry trends, the benefits of tape, the evolution of tape, and security considerations.
The primary function of tape is still backup, but let’s discuss in some detail the different flavors of backup:
- Disaster Recovery (DR)
- Application processing
- Long-term data archiving
- Regulatory and compliance.
A DR backup is the backup you take to ensure that if a disaster strikes, you will be able to recover either at your primary location or at a remote location.
You could simply duplicate your entire DASD farm at an offsite location, but the drawbacks include the high costs and the potential for duplicating errors or mistakes. This means if a file is accidentally deleted or incorrectly updated, the duplex copy also is deleted or incorrectly updated. A duplexed tape-robotic environment means there’s never a delay in getting your backups to the offsite location (since the duplex robot is already offsite), but only a select few data centers can afford this option.
Many companies must balance the risk to the business of the downtime vs. the cost of a duplexing strategy. The balance is between replicating critical applications and data at a failover site vs. the cost of shipping a box or two of cartridges offsite. With capacity now at 500GB per cartridge without compression, a box of compressed high-capacity cartridges can easily represent more than 40TB of backup data.
Cartridge reliability has improved over the years:
- Data stored on the newest high-capacity cartridges is rated at 15 to 30 years, meaning you can set it on the shelf and still read it 15 to 30 years later.
- The new IBM TS1120 cartridges can be loaded and unloaded 20,000 times without failure; that’s five times a day for more than 10 years.
However, moving tape offsite raises certain concerns. Physical movement of cartridges to an offsite location introduces vulnerability of removable media while it’s en route. Currently, more than 30 states have passed laws requiring companies to notify individuals of any security breaches that may affect their personal information.
Over and above compliance issues, now that a single cartridge can hold more than 1TB of data, it’s even more critical that it never be lost. But “never” is a mighty high standard. Encryption addresses compliance as well as helps secure against and limit exposure to industrial espionage. Your data is protected even if it falls into the wrong hands, as it isn’t readable without the proper key to unlock it. With tape encryption, the corporate exposure and liability are dramatically reduced. High-capacity tapes and virtual volume stacking to fill those “fat” tapes have vastly reduced the number of tapes to manage, store and ship. Therefore, many more data centers can now afford to duplex tapes. This has added another level of protection against loss, theft, and defective media.
Another use for tape is application backups. As applications get larger, the amount of data that needs to have a base-line backup is measured in terabytes. While it would be nice to have these backups reside on DASD, the cost-effectiveness of tape makes it a more practical solution. Because of the low cost of tape, there’s no problem taking a “before image” before any application upgrade.