لطفا منتظر باشید ...
Appendix D -- Managing Backup Tapes
If you use tapes as your backup medium, consider the distinction between rotating tapes and archiving tapes. Rotating tapes means reusing them when the data stored on them is no longer viable for restoring. This common practice helps to lower the cost of backing up data. Archiving tapes means storing the tape to keep a record of the data rather than as prevention against data loss. When you archive a tape, you remove that tape from the tape rotation. Archived tapes are useful for maintaining a record of data for a specific date and time, such as employee records at the end of a fiscal year.
Rotating and Archiving Tapes
The following two examples provide strategies for rotating and archiving tapes.
Rotation and Archive Example 1
The following table illustrates one strategy for rotating and archiving tapes and is explained below.
| Monday | Tuesday | Wednesday | Thursday | Friday | |
|---|---|---|---|---|---|
| Week 1 | Tape 1 | Tape 2 | Tape 3 | Tape 4 | Tape 5(Archive) |
| Week 2 | Tape 1(Replace or Append) | Tape 2(Replace or Append) | Tape 3(Replace or Append) | Tape 4(Replace or Append) | Tape 6(Archive) |
Week 1. The backup job for each day of the week is on a different tape. The backup tape for Friday is archived and removed from rotation.Week 2. For this week, you reuse the tapes for the same day of the week (the Monday backup job is on the previous Monday tape 1). You can either replace or append to the existing backup job. However, on Friday, use a new tape that you archive and remove from rotation.
Rotation and Archive Example 2
The following table illustrates another strategy for rotating and archiving tapes and is explained below.
| Monday | Tuesday | Wednesday | Thursday | Friday | |
|---|---|---|---|---|---|
| Week 1 | Tape 1 | Tape 1(Append) | Tape 1(Append) | Tape 1(Append) | Tape 2(Archive) |
| Week 2 | Tape 1 | Tape 1(Append) | Tape 1(Append) | Tape 1(Append) | Tape 3(Archive) |
Week 1. The backup job for each day of the week, except Friday, is on the same tape. The backup tape for Friday is archived and removed from rotation. Use the same tape for the Monday through Thursday backup jobs and append each new backup job to the previous one. The Friday backup job is on a different tape (tape 2) that you archive and remove from rotation.Week 2. For this week, reuse the tape from the previous week (tape 1) for all backup jobs. The Friday backup job is on a tape (tape 3) that is different from the one that you used the previous Friday. You archive and remove this tape from rotation.
Determining the Number of Tapes Required
When determining the number of tapes you need, consider the tape rotation and archival schedule, the amount of the data that you back up, and the tape life cycle.The life cycle of a tape depends on the tape itself and storage conditions. Follow the tape manufacturer's usage guidelines. If your company doesn't have a suitable storage facility, consider using a third-party company that specializes in offsite storage for backup media.
