Example—Monthly Backup Schedule for a Server

The following table shows an example backup strategy for a heavily used file server on a small network where users are doing file-intensive work, such as program development or document production. This example assumes that the backup period begins on a Sunday and consists of four seven-day weeks.

With this schedule, you use 4n tapes, the number of tapes needed for 4 full backups of the root (/), /usr, /export, and /export/home file systems. Also, you need 24 additional tapes for the incremental backups of the /export/home file systems. This schedule assumes that each incremental backup uses one tape and that you save the tapes for a month.

Here's how this schedule works:

1. On each Sunday, do a full backup (level 0) of the root (/), /usr, /export, and /export/home file systems. Save the level 0 tapes for at least three months.

2. On the first Monday of the month, use tape A to do a level 9 backup of the /export/home file system. The ufsdump command copies all files changed since the previous lower-level backup. In this case, the previous lower-level backup is the level 0 backup that you did on Sunday.

3. On the first Tuesday of the month, use tape B to do a level 9 backup of the /export/home file system. Again, the ufsdump command copies all files changed since the last lower-level backup, which is Sunday's level 0 backup.

4. On the first Wednesday of the month, use tape C to do a level 5 backup of the /export/home file system. The ufsdump command copies all files that changed since Sunday.

5. Do the Thursday and Friday level 9 backups of the /export/home file system on tapes D and E. The ufsdump command copies all files that changed since the last lower-level backup, which is Wednesday's level 5 backup.

6. On the first Saturday of the month, use tape F to do a level 5 backup of /export/home. The ufsdump command copies all files changed since the previous lower-level backup (in this case, the level 0 backup you did on Sunday). Store tapes A–F until the first Monday of the next four-week period, when you use them again.

7. Repeat steps 1–6 for the next three weeks, using tapes G–L and 4n tapes for the level 0 backup on Sunday, and so on.

8. For each four-week period, repeat steps 1–7, using a new set of tapes for the level 0 backups and reusing tapes A–X for the incremental backups. The level 0 tapes could be reused after three months.

   This schedule lets you save files in their various states for a month. This plan requires many tapes, but ensures that you have a library of tapes to draw upon. To reduce the number of tapes, you could reuse Tapes A–F each week.