Abstract: A storage system, such as a file server, receives a request to perform a write operation that affects a data block. In response, the storage system writes to a storage device the data block together with context information which uniquely identifies the write operation with respect to the data block. When the data block is subsequently read from the storage device together with the context information, the context information that was read with the data block is used to determine whether a previous write of the data block was lost.

Abstract: A storage controller is operable concurrently as an independent storage server and as at least a portion of a node of a storage server cluster. A network storage system comprises multiple storage controllers and multiple independent storage servers, each storage server implemented in a separate storage controller, each of the storage server configured to present to users a separate system image of stored data. The storage servers are independently operable and manageable. The system further includes a storage server cluster that includes cooperating storage server nodes, distributed among the storage controllers. The storage server cluster presents to users a single system image of data stored in the server cluster independently of the node or nodes in which said data resides. The storage server cluster is operable independently of the independent storage servers and is operable concurrently with operation of at least one of the independent storage servers.

Abstract: A storage system, such as a file server, creates persistent consistency point images (PCPI) or “snapshots” that are point-in-time representations of the storage system. The storage system uses persistent consistency point images to backup or mirror data. Using data already found in the data block maps associated with these PCPI, the rate of change of data between persistent consistency point images can be determined.

Abstract: A storage system, such as a file server, creates persistent consistency point images (PCPI) or “snapshots” that are point-in-time representations of the storage system. The storage system uses persistent consistency point images to backup or mirror data. Using data already found in the data block maps associated with these PCPI, the amount of space used by a set of these consistency points can be determined.

Abstract: A file system receives a request to set a capacity guarantee for a virtual volume associated with a logical aggregation of physical storage. In response, the file system sets the capacity guarantee to indicate that the logical aggregation of physical storage is to provide a specified amount of space to the virtual volume. The amount of space provided to the virtual volume may be based, at least in part, on a guarantee type. The guarantee type may include, for example, volume, file, none, or partial.

Abstract: A storage server maintains multiple file systems in a storage subsystem. A read-only, persistent, point-in-time image of all of the file systems is generated in one atomic operation.

Abstract: A method in a storage system reads blocks having both physical addresses and logical addresses in the storage system from a first set of locations in non-volatile storage to a cache memory and determines the level of data fragmentation in the non-volatile storage. If the level of data fragmentation exceeds a threshold level, the cache memory is marked and the blocks are written to physically sequential locations with new physical addresses in the non-volatile storage at a data consistency point without changing the logical addresses of the blocks.

Abstract: The reserves of a flexible volume and the aggregate which contains the flexible volume are “stacked”. When the flexible volume is created, a portion of the flexible volume having a capacity equal to or less than an unreserved portion of the flexible volume is guaranteed by the aggregate. When the flexible volume creates or modifies metadata, the flexible volume issues a request to the aggregate. The aggregate then issues a portion of the reserve of the aggregate to the flexible volume for storing the metadata.

Abstract: A method in a storage system reads blocks having both physical addresses and logical addresses in the storage system from a first set of locations in non-volatile storage to a cache memory and determines the level of data fragmentation in the non-volatile storage. If the level of data fragmentation exceeds a threshold level, the cache memory is marked and the blocks are written to physically sequential locations with new physical addresses in the non-volatile storage at a data consistency point without changing the logical addresses of the blocks.