Abstract: A method is used in managing updating of metadata of file systems. Changes in metadata of a file of a file system are stored in a journal upon receiving an I/O request for the file of the file system. The I/O request results in update of metadata of the file of the file system. The journal includes metadata transactions upon the file system. Changes to metadata of the file are stored in a volatile memory of a data storage system upon receiving subsequent I/O requests resulting in update of metadata of the file of the file system. Metadata of the file of the file system is updated with information derived from metadata changes stored in the journal.

Abstract: When a file system manager responds to a request to write data to a specified number of blocks of a file, the file system manager determines that corresponding file system data block allocations exist and determines that the file is fragmented over the corresponding file system data block allocations. In response to determining that the file is fragmented over the corresponding file system data block allocations, the file system manager allocates and substitutes a single extent of contiguous file system data blocks for the corresponding file system data block allocations, and writes data to the newly allocated contiguous file system data blocks. For example, the file system manager compares a spread and a count of extent fragments of the file system data block allocations to appropriate thresholds to trigger the defragmentation upon file over-write.

Abstract: Deduplicated data objects are scrubbed by a executing a priority scrubbing task that scans the deduplicated data objects and applies a condition that enables priority data scrubbing based on the value of at least one attribute of the de-duplicated data objects. For example, a low priority task scrubs a deduplicated data object when a reference count of the deduplicated object reaches a threshold. A high priority task scrubs a deduplicated data object when a priority attribute indicates that the deduplicated data object is used by a critical source data object. A medium priority task scrubs a deduplicated data object when the access frequency of the deduplicated data object reaches a threshold. The condition may encode a scrubbing policy or heuristic, and may trigger further action in addition to scrubbing, such as triggering an update of the access rate.