Block Generation

To reduce I/O operations and associated costs, Veeam Backup & Replication will add several days to the immutability expiration date. This period is called Block Generation. You do not have to configure it, the Block Generation setting is applied automatically.

Depending on the type of the object storage repository, Veeam Backup & Replication will add the following values for the default generation period:

  • 30 days — for Amazon S3 object storage and IBM Cloud object storage.
  • 10 days — for all other types of object storage repositories.

For example, if you set your immutability period to 30 days for your object storage repository, Veeam Backup & Replication will add 10 days to specific objects to reduce I/O operations with the data blocks over time. Thus, you will have immutability set for 30 days + 10 days of Block Generation set for data blocks in your object storage repositories.


You can change the default Block Generation period by modifying the registry value on the backup server. For more information, see this Veeam KB article.

How Block Generation Works

When the first data block (a full backup) arrives, its immutability period by default is set to 30 + 10 = 40 days. The first full backup starts its generation, that will be appended with the incremental backups. All the incremental backups within the generation (that is, within the 10-days period) will have the same immutability expiration date as the full backup. For instance, a data block that was offloaded on day 9 will have the same immutability expiration date as a data block offloaded on day 1. Thus we ensure that the immutability period for all the data blocks within a generation is no less than 30 days.

To maintain the backup consistency, Veeam Backup & Replication can extend immutability expiration for all data blocks in all backup chains (both active and inactive) and assign these blocks to a new generation. For example, within one forward incremental backup chain, a full backup file can not be removed before an incremental backup file. On the other hand, an incremental backup file makes no sense without relevant full backup file. So the immutability period is extended for all data blocks in the backup chain.


Consider the following:

  • For data blocks located in object storage repositories, Veeam Backup & Replication extends immutability period for every data block of every backup file in the whole backup chains, even in inactive part.
  • Veeam Backup & Replication will not extended immutability for the data blocks that are not used in any existing backup files.

Page updated 6/12/2024

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