US Patent 9639540 Retention management in a worm storage system

A write-once-read-many, WORM, storage system is arranged to store datasets each with associated attributes including a WORM attribute indicating the dataset's WORM status, and to protect from change or deletion WORM datasets, and at least certain of their attributes including those relevant to WORM status. Retention management capabilities are provided for such a storage system, including the ability to set a given dataset for retention for a particular retention period by storing a corresponding retention date in an attribute of the dataset, and setting the WORM attribute to indicate that the dataset is a WORM dataset. Also provided is the ability to determine expiry of the retention period for the given dataset, and then to remove the stored retention date and change the WORM attribute of the dataset to indicate that it is no longer a WORM dataset.