Operational Defect Database

BugZero found this defect 285 days ago.

Veeam | kb4470

Increase in API Calls when Performing Direct Backups to Immutable Object Storage

Last update date:


Affected products:

Veeam Backup & Replication

Affected releases:


Fixed releases:

No fixed releases provided.



When backing up directly to Object Storage that has immutability enabled, an increase in API callsspecifically PutObjectLockRetention to the Object Storage is noticed. This behavior is observed when using either a simple Object Storage Repository or when targeting a Scale-Out Backup Repository that uses an Object Storage Repository as its Performance Tier. The spike in API calls occurs at regular intervals, typically around every 10 days.


This situation is caused by the way in which backup file immutability is maintained when using Immutable Object Storage as a primary backup destination. As explained in the How Block Generation Works section of the User Guide, Veeam Backup & Replication utilizes Block Generations to extend the immutability of groups of backup files in 10-day intervals (by default). This approach is implemented to reduce I/O operations with the storage over time.


The immutability extension API calls occurring on a 10-day cycle is behavior by design. More information can be found here: How Block Generation Works.

More Information

How to Reduce the Number of Immutability Extension API Calls For most customers, using the software's default settings will be practical and cost-efficient. However, for customers looking to optimize their API vs Storage costs, there are options to shift the cost load from API calls to Storage. It may be possible to reduce overall costs in some cases, but each environment is different, and data size, block size, and immutability requirements must be considered carefully. There are two ways to reduce the overall quantity of API calls needed to maintain immutability. However, while either of these will result in fewer API calls, storage usage will increase.   Option 1: Reduce the Quantity of Blocks by Increasing Block Size To decrease the number of API calls, consider increasing the block size (Storage Optimization) of the backup files generated by jobs that perform direct backups to immutable object storage. Increasing the block size used when creating the backup files will reduce the number of blocks involved in the immutability extension process but will increase the size of the incremental restore points (on average, twice as large). The tradeoff with this method is fewer API calls but more storage usage. Remember that changing the block size (Storage Optimization) used by a backup job will only take effect during the next Active Full backup session. Additionally, if backup copy jobs target the immutable object storage, the block size change must be implemented in the source backup jobs first, followed by forcing an Active Full backup in both the source backup and backup copy jobs.

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