- It must be sufficiently current to meet the requirements of the recovery point objective (RPO)
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- for the system.
- It must be capable of being re-loaded within the recovery time objective (RTO) governing the target system and its data.
- It must be stored in a secure location sufficiently distant from the location of the primary data that it is not likely to be affected by the same interruption event.
The magnetic tape solution
Tape backups are still the most common data backup technique, used since the earliest days of commercial computing. There have always been problems with tape backup, but for a long time, it was the only viable choice for backup.
First and foremost, tape is fragile. In January 1995, Scientific American published an article called "Ensuring the Longevity of Digital Documents," where the physical lifetime of magnetic tape was estimated at 1 year. Too many writes, poor conditions for media storage or transport and an ever-increasing density since the time this article was written can all contribute to increasing read or write errors that can reduce media life to even less than one year. Manual intervention is necessary to verify that backup jobs have completed successfully – and of course this is not always done.
But perhaps the largest drawback to traditional tape backup was the "elastic" RTO and RPO. Once-a-day writing of tape backups is the only feasible possibility, given requirements to actually use the data, and this inevitably resulted in lost transactions and often an inability to meet both the RTO as well as the RPO (which was often listed as "last cycle," but even this was rarely met). Many firms are still doing ineffective tape backups, not realizing that e-vaulting solutions have become quite cost-competitive.
The e-vaulting alternative
E-vaulting technologies are very different from tape backup procedures. There is no daily or cyclical creation of backup tape volumes. All systems work more or less like the following, with variations to meet specific client requirements:
E-vaulting services are now available from a number of third-party firms, many of which have a long track record. All of the primary US recovery site providers, SunGard Data Systems Inc., IBM Corp. and Hewlett-Packard (HP) Co., offer e-vaulting services, as do many regional recovery site providers. A number of reputable e-vaulting-only commercial firms are also available. If you work for a company with a very large systems environment, you are probably already running e-vaulting services internally, (along with high-availability remote mirroring operations for your largest and most critical databases). Small and medium-size firms can choose from a variety of commercial e-vaulting services to meet their particular needs.
If you are now evaluating e-vaulting as a solution for your DR needs, consider the following steps:
- Cost of media for one year
- Cost of hardware (including operating system and power if possible)
- Staff costs for one year (do not forget to factor in benefits)
- Tape pickup and delivery costs for the past year
- Storage costs for the past year.
As with any change of technology, there will be a few bumps along the way, but these should be worked out quickly. As major changes go, this one should be relatively pain-free. And the result will be worth it: your final e-vaulting solution will provide clearly better reliability and much greater flexibility than any tape-based backup solution. No matter what your data backup needs, you should be able to find an e-vaulting solution that scales either up or down to meet your individual requirements with costs that may be a pleasant surprise.
Remember that the shelf life of disk media is about five years as compared to one year or less for tape media. And if you need to hold archive data for more than five years, consider paper, microform or optical media.
Kathleen Lucey, FBCI, is the president of Montague Risk Management and is president of the Business Continuity Institute USA Chapter.
This was first published in September 2008