Abstract: Embodiments are described for detecting a data organization issue in a storage system by analyzing static and dynamic layout characteristics for data stored in the storage system, workload characteristics for applications utilizing the data, virtualization effects of the storage system on the organization of the data, input/output characteristics of processes storing the data in the storage system, and cache usage characteristics of the data. For fragmentation issues, the system uses the analysis to provide defragmentation advisories to reduce fragmentation by at least one of: re-layout or re-tiering of the data in the data storage system, or cache memory reconfiguration.

Abstract: Described are techniques for correcting at least some inconsistencies in a file system accessed by at least one client, while maintaining the file system online. A file system checking utility is executed on the file system to detect and create corrections for inconsistencies in the file system. The file system is updated to include at least some corrections. Also described is a computer system comprising a file system accessed by a client. A file system checking utility is executed on the file system to detect at least some inconsistencies in the file system, and to create a corrected version of the file system that includes corrections to correct for at least some of the detected inconsistencies. A report is created. The file system is not updated with the corrected version unless the proposed corrections are approved. The file system checking utility may be periodically scheduled for execution.

Abstract: A file server architecture decouples logical storage from physical storage and provides proactive detection and containment of faults, errors, and corruptions in a file system, in order to enable in place (online) and non-intrusive recovery. The file system is built upon a thinly provisioned logical volume, and there are stored three copies of the metadata defining the logical volume in order to provide quick, deterministic, and reliable recovery from a faulted system. A first copy of the metadata is distributed among all of the slices of physical storage allocated to the logical volume. A second copy of the metadata is stored in a root slice of the logical volume. A third copy of the metadata is stored separate from the slices of physical storage allocated to the logical volume.

Abstract: A file server maintains a production file system supported by a clone volume, and multiple snapshot file systems supported by respective save volumes in a snapshot queue. Before a data block is modified for the first time after creation of the youngest snapshot, the data block is copied from the clone volume to the save volume of the youngest snapshot. A bit map indicates the blocks that have already been copied, and a block map shows the save block address for each corresponding clone block address. When a new snapshot is created, the bit and block maps are converted to a hash index that is kept linked to the save volume of what had been the youngest snapshot. When other than the oldest snapshot file system is deleted, the respective save volume is retained as a hidden object until it becomes the oldest save volume.