The following table provides guidelines for scheduling backups. For additional backup schedule considerations, see Considerations for Scheduling Backups.
Table 24–6 Guidelines for Backup Schedules
File Restoration Need |
Backup Interval |
Comments |
---|---|---|
To restore different versions of files (for example, file systems that are used for word processing) |
Do daily incremental backups every working day. Do not reuse the same tape for daily incremental backups. |
This schedule saves all files modified that day, as well as those files still on disk that were modified since the last backup of a lower level. However, with this schedule, you should use a different tape each day because you might otherwise be unable to restore the needed version of the file. For example, a file that changed on Tuesday, and again on Thursday, goes onto Friday's lower-level backup appearing as it did Thursday night, not Tuesday night. If a user needs the Tuesday version, you cannot restore it unless you have a Tuesday backup tape (or a Wednesday backup tape). Similarly, a file that is present on Tuesday and Wednesday, but removed on Thursday, does not appear on the Friday lower-level backup. |
To quickly restore a complete file system |
Do lower-level backups more frequently. |
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To back up a number of file systems on the same server |
Consider staggering the schedule for different file systems. |
This way you're not doing all level 0 backups on the same day. |
To minimize the number of tapes used |
Increase the level of incremental backups that are done across the week. |
Only changes from day to day are saved on each daily tape. |
|
Increase the level of backups that are done at the end of the week. Put each day's and week's incremental backups onto the same tape. |
Only changes from week to week (rather than the entire month) are saved on the weekly tapes. |
|
Put each day's and week's incremental backups onto the same tape. |
To do so, use the no rewind option of the ufsdump command, such as specifying /dev/rmt/0n. |