Abstract: Examples include the persistent storage of cached data of a write to a block device presentation. Some examples may include a block device presentation of data represented by first backup objects stored in a deduplication backup appliance, and may cause the deduplication backup appliance to store second backup objects representing the data stored in a cache for each transient write to the block device presentation.

Abstract: 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.

Abstract: 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.

Abstract: A clustered storage system includes a machine arranged to check, using its own clock as a current time reference, for expiry of a retention period set for a dataset stored in the system. In order to monitor for any interference with its clock, the expiry-checking machine obtains from other machines of the system, the current times of their clocks, and then derives a value from these times which it compares with a current time value from its own clock; where the difference between these values exceeds a predetermined amount, the expiry-checking machine generates an alert. This monitoring process is carried out repeatedly.