TAPE BACKUP STRATEGIES

29. April 2011, 19:55 | by WD Milner | Full Article |

In this day and age of massive inexpensive hard drives high capacity optical disks and flash media an older option for backup is often overlooked; that is except among organizations that need very large scale archival storage. I’m talking about magnetic tape. Always somewhat out of the mind of consumers and small businesses, tape backup has long been a mainstay of archival storage for larger enterprises, organizations such as universities and research centres and government agencies and departments.

Tape has some distinct advantages for high-capacity, long-term storage. It is relatively inexpensive, has an excellent longevity if stored properly, is reasonably rugged and easily transportable. While I’m not going to get into all the different tape options and their pros and cons, I would like to offer a look at various back-up strategies using tape as the medium of choice. The following strategies assume a 6 day work week, Monday through Saturday. This can be adjusted as needed to suit specific circumstances.

3 Tape Rotation

If your files don’t change much from day to day, a three tape rotation strategy may be adequate. In this system, you do a total backup on Monday using Tape 1. Daily backups of modified files are made on Tuesday to Saturday. On the following Monday, do a total backup using Tape 3 and move Tape 1 off site for storage. Erase Tape 2 and repeat daily backups of modified files.

Three Tape Rotation
MondayTuesdayWednesdayThursdayFridaySaturdayOff Site
TotalModifiedModifiedModifiedModifiedModifiedTotal
Tape 1Tape 2Tape 2Tape 2Tape 2Tape 2Tape 3

7 Tape Rotation

If you files change daily, consider a seven tape rotation. Label six tapes Monday through Saturday and a seventh "Off Site". On Monday do a total backup on the 'Monday' tape. From Tuesday through Saturday, do backups on each days tape of all modified files. At the end of the week, do a total backup on the "Off Site" tape.

Seven Tape Rotation
MondayTuesdayWednesdayThursdayFridaySaturdayOff Site
TotalModifiedModifiedModifiedModifiedModifiedTotal
Tape 1Tape 2Tape 3Tape 4Tape 5Tape 6Tape 7

11 Tape Rotation

If you need to preserve weeks or months worth of data consider a ten tape rotation. this is similar to the seven tape rotation method except that you add four tapes to do separate total backups at the end of each week and retain them for a month's worth of data. Note that this method can be easily extended with another “layer” to provide a full year of backups.

Eleven Tape Rotation
Weekly
MondayTuesdayWednesdayThursdayFridaySaturdayOff Site
TotalModifiedModifiedModifiedModifiedModifiedTotal
Tape 1Tape 2Tape 3Tape 4Tape 5Tape 6Tape 7

Off Site
Week 1Week 2Week 3Week 4Monthly
Tape 7Tape 8Tape 9Tape 10Tape 11

General Considerations

  • Do a total backup weekly and modified backups daily.
  • Label tape cartridges clearly so you will know which tapes to restore should the need arise.
  • Tapes wear out so rotate new tapes into your schedule. Keep at least one new tape on hand for each layer.
  • Store tapes in cases or caddies, preferably on edge, and keep them away from magnetic fields and extremes of heat.
  • Clean tape drive heads after about 20 backup and/or restores and periodically retension tapes.
  • Store a weekly total backup off site in case of fire, flood, or theft.
  • Archive seldom used files to tape to make efficient use of hard drive space.
  • Automate backups with schedulers and/or scripts.
  • Do regular compare operations to verify proper tape drive function.

Whichever backup strategy you choose, it is also a good idea to have one or more archive tapes. By moving files to an archive tape, you can safeguard those time-intensive reports and presentations, or anything else on disk that you would like to remove, but still have access to, including programs. Regardless of backup method chosen, The key to saving valuable data is to follow your chosen strategy faithfully.

Is an investment in tape backup worth it? You have already spent thousands of dollars on a computer system, peripherals and software. Without some form of backup, there is a very real danger that all your data could disappear in a flash. You would have to reload all your software from scratch, taking from a few minutes to a few hours, or a few days. Then you probably have customized interfaces, macros or formats you would have to recreate. That would take a few more hours or days. But the data is the hard part. Some files you could undoubtedly do without but many would have to be recreated from hard copy, or from your memory. Additionally, by backing up seldom used files, one can preserve hard drive space for more important data.

According to some studies, it would take an average personal computer user between one and two weeks to recreate data lost through hardware failure, negligence, computer virus, natural disaster or other causes. Servers even longer. The average cost of recreating 10 GB of sales and marketing data can reach or exceed approximately $50-75,000. For accounting data that rises to $100-150,000. And for engineering data a whopping $200-300,000. Additional costs can include worry, stress, inconvenience, lost work and lost business. Half of all companies that experience downtime lasting 15 days or more have gone out of business or been sold within a year.

Why back up your hard drive? the answers should be obvious but few individuals, and even many businesses don’t bother.

  • The human eraser. It is easy to overwrite a file by mistake.
  • Hard disk failure. Hard drives age and eventually fail. They can be damaged unpredictably by moving or shipping.
  • Fire or theft. With a single copy of data on site your information becomes very vulnerable.
  • Power problems. Sudden power loss or fluctuations can cause numerous disk problems resulting in unrecoverable data loss.
  • Packed disk. That endless disk will fill up more rapidly than you might realize. Moving files off line can free up needed space.

- 30 -

Categories: ,
Keywords: backup,tape,security,loss risk

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