摘要:
A data storage system is constructed to rapidly respond to a physical backup request for backup of a physical storage unit such as a disk volume or cylinder. A user, however, may request backup of a logical data structure such as a file having a rather complex mapping to a number of physical storage components such as a number of disk tracks. For backup and restore of such a logical data structure, a backup agent requests an application interface routine to backup a physical storage unit that includes the logical data structure. The application interface routine issues a corresponding physical backup request to the data storage system, and creates a catalog of information about content of the physical storage unit that would be needed for restoring the logical data structure from the backup version of the physical storage unit. Later, if and when the backup agent requests the restoration of the logical data structure, the application interface routine looks up the logical data structure in the catalog, issues a physical restore request to the data storage system to retrieve a backup version of the physical storage unit from backup data storage and load it into spare data storage, extracts the logical data structure from the physical storage unit in the spare data storage by performing a logical-to-physical translation, and restores the logical data structure into the current version of data storage.
摘要:
A data storage system has a primary data storage subsystem including primary data storage and a secondary data storage subsystem including secondary data storage. The secondary data storage contains backup versions of data stored in the primary data storage. To permit a host processor to access a specified backup version, the primary data storage subsystem assigns a virtual storage address to a specified backup version, and the host processor sends to the primary data storage subsystem data access requests that specify the virtual storage address. If the primary data storage subsystem has spare data storage, then a copy of the specified backup version is read from the secondary storage and written into the spare storage, and the address of the copy in the spare storage is mapped to the virtual storage address and accessed in response to the storage access requests from the host processor. Otherwise, a block-level direct access of the secondary storage is performed to access the specified backup version. In either case, the backup version appears to be in the primary data storage subsystem when the host accesses it.
摘要:
A video file server includes an integrated cached disk array storage subsystem and a plurality of stream server computers linking the cached disk array to a data network for the transfer of video data streams. The video file server further includes a controller server for applying an admission control policy to client requests and assigning stream servers to service the client requests. The stream servers include a real-time scheduler for scheduling isochronous tasks, and supports at least one industry standard network file access protocol and one file access protocol for continuous media file access. The cached disk storage subsystem is responsive to video prefetch commands, and the data specified for a prefetch command for a process are retained in an allocated portion of the cache memory from the time that the cached disk storage subsystem has responded to the prefetch command to the time that the cached disk storage subsystem responds to a fetch command specifying the data for the process. The time between prefetching and fetching is selected based on available disk and cache resources. The video file server provides video-on-demand service by maintaining and dynamically allocating sliding windows of video data in the random access memories of the stream server computers. The video file server has a tape silo for providing network backup services, and data to be written to tape are prestaged in the cached disk storage subsystem.
摘要:
A primary data storage subsystem has primary data storage and a storage controller for controlling access of host processors to the primary data storage. The primary data storage subsystem is linked to a secondary data storage subsystem for transfer of backup data between the primary data storage subsystem and the secondary data storage subsystem. The secondary data storage subsystem has a tape library unit for storing the backup data. A host processor usually accesses the primary storage. A host can also send backup and restore commands to the storage controller, to cause specified data from the primary storage to be written as a backup version in the tape library unit, and to cause a specified backup version to be read from the tape library unit to be accessible to the host from the primary data storage unit. In this fashion, the host need not be concerned with the basic operations of the tape library unit. A host, however, can send backup media remote control requests to the storage controller, and the storage controller responds by sending corresponding backup media remote control commands to the tape library unit, to permit the host to control remotely the basic operations of the tape library unit. Therefore, the host can obtain status of read/write stations in the tape library unit, and control the mounting, unmounting, and transport of the tapes mounted at the read/write stations.
摘要:
A data storage system is constructed to rapidly respond to a backup request by streaming backup data from primary storage to tape. It is desirable to permit the data to be removed from the primary storage at a faster rate than it can be written to tape. The backup data is buffered in a memory buffer, and when the memory buffer becomes substantially full, a portion of the backup data is buffered in disk storage. When the memory buffer becomes substantially empty, the portion of the backup data in the disk storage is written to tape. In a preferred embodiment, the memory buffer is in random access memory of a data mover computer that transfers the backup data from primary storage to a tape library unit. When the memory buffer becomes full, the data mover stores the overflow in a cached disk storage subsystem. When the memory buffer becomes empty, the data mover retrieves the overflow from the cached disk storage subsystem and transmits the overflow to the tape library unit. In this fashion, the sequence of data tracks as stored on the tape can be different from the sequence of data tracks as stored in the primary storage. To facilitate restoration of the primary storage with a backup version, the data tracks as stored in records on the tape are identified by a track number included in each record on the tape.