Using Arcserve UDP Agent (Linux) › How to Back up Linux Nodes › Configure the Backup Settings and Run Backup Job › Specify the Advanced Settings › Understanding the Types of Backup

Understanding the Types of Backup

You can specify the following types of backup in the Advanced page of the Backup Wizard:

Incremental Backup

Backs up only those blocks that have changed since the last successful backup. The advantages of Incremental Backup are that it is a fast backup and it produces a small backup image. Arcserve Unified Data Protection Agent for Linux uses a driver to monitor the changed blocks in the source node since the last successful backup.

The available options are Repeat and Never. If you select the Repeat option, you must also specify the elapsed time period (in minutes, hours, or days) between backup attempts.

Minimum: 15 minutes

Default: 1 day

Full Backup

Backs up the entire source node. Depending on the volume size of the backup node, Full Backup produces a large backup image and usually takes a longer time to complete. The available options are Repeat and Never.

If you select the Repeat option, you must also specify the elapsed time period (in minutes, hours, or days) between backup attempts.

Minimum: 1 day

Default: Never (no scheduled repeat)

Verify Backup

Verifies that the protected data is valid and complete by performing a confidence check of the stored backup image to the original backup source. If necessary, the image is resynchronized. A Verify Backup looks at the most recent backup of each individual block and compares the content and information to the source. This comparison verifies that the latest backed up blocks represent the corresponding information at the source. If the backup image for any block does not match the source (possibly because of changes in the system since the last backup), Arcserve Unified Data Protection Agent for Linux refreshes (resynchronizes) the backup of the block that does not match. You can also use a Verify Backup (very infrequently) to get the guarantee of full backup without using the space required for a full backup.

Advantages: Produces a small backup image when compared to full backup because only the changed blocks (blocks that do not match the last backup) are backed up.

Disadvantages: Backup time is long because all source blocks are compared with the blocks of the last backup.

The available options are Repeat and Never. If you select the Repeat option, you must also specify the elapsed time period (in minutes, hours, or days) between backup attempts.

Minimum: 1 day

Default: Never (no scheduled repeat)

The type of backup that runs depends on the following situations:

• If you run the backup job for the first time for the selected nodes, the first backup is always a Full Backup.
• If you run the backup job again for the same set of nodes and the backup destination is also same, the backup type is Incremental Backup.
• If you run the backup job for the same set of nodes but the backup destination is different, the backup type is Full Backup. This is because you have changed the backup destination and for the new destination this is the first backup. So, the first backup is always a Full Backup.
• If you delete your node and then add the same node again but you do not change the backup destination, the backup will be a Verify Backup. This is because you have already backed up that node in your previous backup jobs. When you delete the node and then you add the node again, the backup job verifies all the blocks of that node with the last backup image. When the backup job decides that it is the same node then it backs up only the changed blocks. If the backup job does not find any backup image of that node in the backup destination, the backup type is a Full Backup.