Features and principles of Bacula of open source network backup software

First, what is Bacula?

Bacula is an open source Cross-platform network Backup tool that provides a backup recovery solution based on an enterprise-class client/server that enables system administrators to back up, restore, and integrity verify data, while providing many advanced storage management features, Makes it easy for system administrators to discover and recover missing or corrupted files. Bacula is available in both the Windows version and the Linux and UNIX versions.

Second, Bacula for which users

If your business system has a huge amount of data and is growing rapidly every day, and you need to do a low-level backup with tar packaging, and you don't have a corresponding disaster recovery strategy, you should consider using Bacula. Bacula has a perfect incremental backup function, while also supporting remote disaster recovery backup. By Bacula, data can be backed up to any remote host, and the user needs to simply set up the Bacula to automate the data backup.

If a user already has a storage device, such as a disk array, tape/band library, and just need to automatically back up business data from the server to these storage devices, Bacula is certainly the best choice because Bacula has media management capabilities, It makes it easy to save server data to one or more mounted tapes or libraries. Although commercial backup software can also complete the automatic backup of data to storage devices, but costly.

For users who are using a commercial backup software such as Legato and Veritas, you should try Bacula, because Bacula can match these commercial software, and more importantly, Bacula is open source software, if some key functions are not implemented, You can choose how to modify the open source software code to implement it. By making simple changes to open source software to meet special needs, the user's work is greatly simplified.

Three, the function characteristic of Bacula

1. Supports multiple backup methods

(1) Full backup

A full backup is a complete backup of business data. For example, Monday uses a tape to back up the entire business system, Tuesday with another tape to back up the entire business system, and so on.

The advantage of this backup strategy is that when data loss occurs, the lost data can be recovered by using just one tape (that is, the backup tape from the day before the disaster occurs). Of course, it also has deficiencies. First of all, due to a full backup of the entire system every day, the backup data will inevitably result in a large number of duplication. These duplicate data occupy a lot of tape space, which means more cost to the user. Second, if the amount of data backed up is large, then the backup takes longer. For some businesses that are busy and have limited backup time, it is unwise to choose this backup strategy.

(2) Incremental backup

An incremental backup is a backup that is based on the last backup, meaning that only new or modified data is backed up on a daily basis, for example, a full backup in Sunday, a backup of the data from Sunday to Monday in Monday, and a Tuesday backup of the data added from Monday to Tuesday, and so on.

The advantage of this backup strategy is that only the updated or increased data on the day is backed up, resulting in a small amount of data, saving tape space and shortening backup time. Of course, it has its drawbacks as well. When a disaster occurs, the recovery process of the data is more cumbersome. If the system fails in the morning of Friday and loses a large amount of data, it is now time to restore the system to its Thursday state. The system administrator first finds the Sunday full backup for system recovery, then finds the Monday backup to recover the Monday data, then finds the Tuesday backup to restore the Tuesday data. In this way, until the Thursday data is restored, it is clear that this is a cumbersome approach. The reliability of backups is also poor. In this way of backup, the relationships between each backup are like a chain, and each one of these backups is a problem that causes the chain to be disconnected. In the example above, if a Wednesday backup fails, the administrator can only restore the system data to the Tuesday state.

(3) Differential backup

Differential backups are a way of backing up on a full backup basis. For example, a system administrator makes a full backup of the system in Sunday, backs up data from Sunday to Monday in Monday, and then backs up the data between Tuesday and Sunday in Tuesday, and so on, that is, back up all the data (new or modified) that were different from Sunday on the same day.

Differential backup avoids the drawbacks of the above two backup strategies, and it has all the benefits of both backup methods. First, it does not have to do a full backup of the system every day, as a result, backup data is small, backups take a short time, and space is saved, and second, it is handy for disaster recovery, which requires only two backups, that is, a full backup and a backup of the day before the disaster, to restore the system.

In fact, each backup method is not isolated, in the actual backup applications, the above three methods are usually combined with the backup strategy. For example, an incremental or differential backup is performed every Monday to Saturday, a full backup every Sunday, a full backup at the end of each month, and a full backup at the end of the year.

By introducing the three backup methods, you can tell that the amount of data for each backup is different: Full backup > Differential backup > Incremental backup. As a result, the data used in data recovery is different. If you use the full backup method, all data can be recovered simply by taking advantage of the last full backup; If you use full backup + incremental backup, you need to take advantage of the last full backup + all incremental backups after the last full backup to recover all the data; If you use full backup + differential backup, You only need to take advantage of the last full backup + The most recent differential backup to recover all the data.