System Administration Guide: Devices and File Systems

Sample Backup Schedules

This section provides sample backup schedules. All schedules assume that you begin with a full backup (dump level 0), and that you use the -u option to record each backup in the /etc/dumpdates file.

Example—Daily Cumulative, Weekly Cumulative Backup Schedule

Table 23–7 shows the most commonly used incremental backup schedule. This schedule is recommended for most situations. With this schedule, the following occurs:

Table 23–7 Daily Cumulative/Weekly Cumulative Backup Schedule
 

Floating 

Mon 

Tues 

Wed 

Thurs 

Fri 

1st of Month 

 

 

 

 

 

Week 1 

 

Week 2 

 

Week 3 

 

Week 4 

 

The following table shows how the contents of the tapes can change across two weeks with the daily cumulative, weekly cumulative schedule. Each letter represents a different file.

Table 23–8 Contents of Tapes for Daily Cumulative/Weekly Cumulative Backup Schedule
 

Mon 

Tues 

Wed 

Thurs 

Fri 

Week 1  

a b 

a b c 

a b c d 

a b c d e 

a b c d e f 

Week 2  

g h 

g h i 

g h i j 

a b c d e f g h i j k 

Tape Requirements for the Daily Cumulative, Weekly Cumulative Schedule

With this schedule, you need six tapes if you want to reuse daily tapes. However, you need nine tapes if you want to use four different daily tapes:

If you need to restore a complete file system, you need the following tapes:

Example—Daily Cumulative, Weekly Incremental Backup Schedule

The following table shows a schedule where each weekday tape accumulates all files that changed since the beginning of the week, or the initial level 0 backup for the first week. In addition, each Friday's tape contains all the files that changed that week.

Table 23–9 Daily Cumulative, Weekly Incremental Backup Schedule
 

Floating 

Mon 

Tues 

Wed 

Thurs 

Fri 

1st of Month 

 

 

 

 

 

Week 1 

 

Week 2 

 

9  

Week 3 

 

Week 4 

 

The following table shows how the contents of the tapes can change across two weeks with the daily cumulative, weekly incremental backup schedule. Each letter represents a different file.

Table 23–10 Contents of Tapes for Daily Cumulative, Weekly Incremental Backup Schedule
 

Mon 

Tues 

Wed 

Thurs 

Fri 

Week 1  

a b 

a b c 

a b c d 

a b c d e 

a b c d e f 

Week 2  

g h 

g h i 

g h i j 

g h i j k 

Tape Requirements for the Daily Cumulative, Weekly Incremental Backup Schedule

With this schedule, you need six tapes if you want to reuse daily tapes. However, you need nine tapes if you want to use four different daily tapes:

If you need to restore a complete file system, you need the following tapes:

Example—Daily Incremental, Weekly Cumulative Backup Schedule

The following table shows a schedule where each weekday tape contains only the files that changed since the previous day. In addition, each Friday's tape contains all files changed since the initial level 0 backup at the beginning of the month.

Table 23–11 Daily Incremental, Weekly Cumulative Backup Schedule
 

Floating 

Mon 

Tues 

Wed 

Thurs 

Fri 

1st of Month 

 

 

 

 

 

Week 1  

 

Week 2  

 

Week 3  

 

Week 4 

 

The following table shows how the contents of the tapes can change across two weeks with the daily incremental, weekly cumulative schedule. Each letter represents a different file.

Table 23–12 Contents of Tapes for Daily Incremental, Weekly Cumulative Backup Schedule
 

Mon 

Tues 

Wed 

Thurs 

Fri 

Week 1  

a b 

c d 

e f g 

hi 

a b c d e f g h i 

Week 2 

 

j k l 

n o 

p q 

a b c d e f g h i j k l m n o p q r s 

Tape Requirements for Daily Incremental, Weekly Cumulative Schedule

With this schedule, you need at least 9 tapes if you want to reuse daily tapes, which is not recommended. Preferably, you need 21 tapes if you save weekly tapes for a month: one tape for the level 0, 4 tapes for the Fridays, and 4 or 16 daily tapes.

If you need to restore the complete file system, you need the following tapes:

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.

Table 23–13 Example of Monthly Backup Schedule for a Server

Directory 

Date 

Dump Level 

Tape Name 

root (/)

1st Sunday 

n tapes

/usr

1st Sunday 

n tapes

/export

1st Sunday 

n tapes

/export/home

1st Sunday 

n tapes

 

1st Monday 

 

1st Tuesday 

 

1st Wednesday 

 

1st Thursday 

 

1st Friday 

 

1st Saturday 

root (/)

2nd Sunday 

n tapes

/usr

2nd Sunday 

n tapes

/export

2nd Sunday 

n tapes

/export/home

2nd Sunday 

n tapes

 

2nd Monday 

G  

 

2nd Tuesday 

H  

 

2nd Wednesday 

I  

 

2nd Thursday 

J  

 

2nd Friday 

 

2nd Saturday 

L  

root (/)

3rd Sunday 

n tapes

/usr

3rd Sunday 

n tapes

/export

3rd Sunday 

n tapes

/export/home

3rd Sunday 

n tapes

 

3rd Monday 

 

3rd Tuesday 

N  

 

3rd Wednesday 

O  

 

3rd Thursday 

 

3rd Friday 

 

3rd Saturday 

root (/)

4th Sunday 

n tapes

/usr

4th Sunday 

n tapes

/export

4th Sunday 

n tapes

/export/home

4th Sunday 

n tapes

 

4th Monday 

 

4th Tuesday 

 

4th Wednesday 

 

4th Thursday 

 

4th Friday 

 

4th Saturday 

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.