Backup Strategies

投稿者: | 2014年6月11日

Backup Strategies

Although Recycling and Backing Up to Disk Volume have been discussed in previous chapters, this chapter is meant to give you an overall view of possible backup strategies and to explain their advantages and disadvantages.

Simple One Tape Backup

Probably the simplest strategy is to back everything up to a single tape and insert a new (or recycled) tape when it fills and Bacula requests a new one.

Advantages

The operator intervenes only when a tape change is needed. (once a month at my site).
There is little chance of operator error because the tape is not changed daily.
A minimum number of tapes will be needed for a full restore. Typically the best case will be one tape and worst two.
You can easily arrange for the Full backup to occur a different night of the month for each system, thus load balancing and shortening the backup time.
Disadvantages

If your site burns down, you will lose your current backups, and in my case about a month of data.
After a tape fills and you have put in a blank tape, the backup will continue, and this will generally happen during working hours.
Practical Details

This system is very simple. When the tape fills and Bacula requests a new tape, you unmount the tape from the Console program, insert a new tape and label it. In most cases after the label, Bacula will automatically mount the tape and resume the backup. Otherwise, you simply mount the tape.

Using this strategy, one typically does a Full backup once a week followed by daily Incremental backups. To minimize the amount of data written to the tape, one can do a Full backup once a month on the first Sunday of the month, a Differential backup on the 2nd-5th Sunday of the month, and incremental backups the rest of the week.

Manually Changing Tapes

If you use the strategy presented above, Bacula will ask you to change the tape, and you will unmount it and then remount it when you have inserted the new tape.

If you do not wish to interact with Bacula to change each tape, there are several ways to get Bacula to release the tape:

In your Storage daemon’s Device resource, set AlwaysOpen = no In this case, Bacula will release the tape after every job. If you run several jobs, the tape will be rewound and repositioned to the end at the beginning of every job. This is not very efficient, but does let you change the tape whenever you want.
Use a RunAfterJob statement to run a script after your last job. This could also be an Admin job that runs after all your backup jobs. The script could be something like:
#!/bin/sh
/full-path/bconsole -c /full-path/bconsole.conf <

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