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Are there any guidelines for Backup, Archiving and Data Recovery?
(KB # 592B8E1D)

Regular tape backup is one of the essential components of protecting your data. Backup can be conducted in many different ways, and can rely on any one of many different software applications or user-written scripts. To ensure reliability of your backups and recoverability of your data, it is important to follow a handling and rotation schedule to create multiple redundant copies and preserve changing and evolving file versions.

Recommendations for backup

  1. Verify that your backup data can be recovered.
  2. Create a version history.
  3. Store backup copies off-site.
  4. Have a management system in place.

Backup Rotation Schemes

To ensure recovery of your data you should adopt a systematic tape rotation schedule. Your rotation schedule should provide you with a long and varied history of file versions. You should arrange secure off-site storage for any media that are not in active use.

Tandberg Data recommends that you use one of the regular rotation schedules described below. Both provide a file versions and are offered as backup patterns by most backup application software packages.

Daily-Weekly-Monthly Backup - DWM

Daily-Weekly-Monthly Backup is the most commonly used media rotation schedule. This scheme uses daily, weekly, and monthly backup sets. The use of these three sets is explained below:

  1. DAILY: Five or six sets of tapes are used, one for each day of the week. Note that each of these "sets" may be a single tape or a set of tape, depending on the amount of data saved. These are the "Daily" tapes and each set of media is labeled Monday through Friday-Saturday. Typically, incremental backups are performed on each "Daily" group of tapes. Each set of media is reused each week on the day matching its label.
  2. WEEKLY: A set of up to five weekly backup tapes are labeled "Week1," "Week2," etc. As with the daily tapes, each "set" can be either one tape or a set of tapes. Full backups are recorded weekly, normally on a Saturday or Sunday, on the day that the "Daily" tapes are not used. These "Weekly" media are reused monthly.
  3. MONTHLY: The final set of three backup tapes are labeled "Month1," "Month2," etc., according to which month of the quarter each will be used. This "Monthly" media record full backups on the last business day of each month and are reused quarterly.

A total of 12 media sets are required for this basic rotation scheme, allowing for a history of two to three months. Because a longer history is often required, archive tapes are periodically created and stored in an off-site secure facility.

Multi-Level Media - MLM

The MLM rotation scheme is also widely used. In this schedule, one tape set "A" is used every other backup session (daily sessions in this example). Start Day 1 with "A" and repeat every other backup (every other day). The next tape set "B" starts on the first non-"A" backup day and repeats every fourth backup session. Tape set "C" starts on the first non-"A" or non-"B" backup day and repeats every eighth session. Tape set "D" starts on the first non-"A," non-"B or non- " C" backup day and repeats every sixteenth session. Tape set "E" alternates with tape set "D."

With each additional tape set added to the rotation scheme, the backup history doubles. The frequently used tape sets have the most recent copies of a file, while less frequently used tapes retain older versions. This schedule can be used in either a daily or weekly rotation scheme. The decision regarding the frequency of rotation should be based on the volume of data volume. To maintain the required history of file versions, a minimum of five tape sets should be used in the weekly rotation schedule, or eight for a daily rotation scheme. As with the Daily- eekly-Monthly rotation scheme, periodically tapes should be archived and stored in a secure off-site facility.

Monday Tuesday Wednesday Thursday Friday
A - tape B - tape C - tape D - tape E - tape
Saturday Sunday Monday Tuesday Wednesday
A - tape B - tape C - tape D - tape E - tape


A data archival program is critical to your business health, as well as essential for legal reasons, and helps you to manage data that is kept for extended time periods. For business security we recommend archival of tapes in addition to routine backup.

Because of the importance of this program, we recommend off-site storage in an environmentally controlled, secure data storage facility.

It is important to distinguish between data in archive and tapes in archive. By keeping multiple copies of data on a single piece of tape, you leave that data at risk. Tape redundancy is vital for data security.

Data Retention Recommendation

The Standards for Data Retention vary by application, state, and country. In general, they range from three years to permanent.

Caution: Confirm your record storage requirements! This section is an example only.

You should maintain redundant copies of business data long term. We recommend you store archive copies of all on-line data, in addition to backups, to ensure compliance with government or insurance regulations.

Recommendations for Tape Archival

Listed below are recommendations for the archive program that will result in safely rotecting your data and giving you long-term success.

  1. Use Tandberg Data tape. Your data is an irreplaceable asset, and the cost of loss far outweighs the investment in protection.
  2. Store multiple copies of your valuable data on multiple pieces of tape.
  3. For long-term archive, store the recording systems (and all components) as well as the tapes.
  4. Consider data to be archived as soon as it is stored on tape.
  5. Record your archive data using the verification feature in your software.
  6. Retain archive data for a period of time appropriate to the legal standards for the type of data you are protecting. You may need to retain data permanently.
  7. Long-term archives need to be stored in a secure, environmentally controlled facility as an extension of your in-house media library or shelf storage.
  8. Tape management should be employed to track the tapes in backup, archive, and disaster recovery roles.
  9. Periodically inspect archived tapes.

Recommendations for Data Recovery

Listed below are recommendations for a disaster recovery program.

  1. Make sure your off-site storage facility meets the environmental storage requirements for archive noted above.
  2. If you have operations and data vulnerable to loss, move the tapes off-site daily. Use a service bureau or do it yourself if you have the facility.
  3. Remote means off-site, with enough distance from the using site to be removed from local disaster area.
  4. Ensure that you have adequate redundancy in your off-site backup pool for disaster recovery. Tandberg Data recommends planning tape archival redundancy into your tape storage requirements.
  5. Periodically retire tapes. Plan retirement into your media management plan.

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