Optimizing retention of deduplicated copies at write-once read-many (WORM)-enabled storage

A system comprising one or more computing devices, which configure the system to:

• generate a first plurality of deduplicated backup copies, which are stored at a storage platform that provides write-once read-many (WORM) data storage,
• wherein the storage platform is configured for bucket-level data storage, and
• wherein the system associates the first plurality of deduplicated backup copies with a first deduplication database, and
• wherein the system is configured with a retention period for deduplicated backup copies, and is further configured with a sealing interval for deduplication databases;
• cause a storage bucket at the storage platform to be configured with a WORM lock duration that comprises a sum of the sealing interval and the retention period,
• wherein the WORM lock duration applies to each deduplicated backup copy among the first plurality of deduplicated backup copies stored at the storage bucket, and wherein the WORM lock duration starts when a respective deduplicated backup copy is stored in the storage bucket;
• based on determining that the sealing interval has passed in reference to the first deduplication database, cause the first deduplication database to be sealed;
• and
• based on determining that the first deduplication database has been sealed, and further that the storage platform released a WORM lock on at least one deduplicated backup copy among the first plurality of deduplicated backup copies according to the WORM lock duration, initiate pruning of the at least one deduplicated backup copy from the storage bucket;
• wherein sealing the first deduplication database comprises deactivating the first deduplication database, which indexes data blocks referenced by the first plurality of deduplicated backup copies, and further comprises activating a second deduplication database for indexing data blocks of a second plurality of deduplicated backup copies that are generated subsequent to the first plurality of deduplicated backup copies.