摘要:
A method for using existing internal mapping mechanisms to dynamically map data in a computer storage subsystem is provided. The invention comprises using a dynamic mapping mechanism to mark (e.g., via a D-Mark) a data location and then using pointers to direct write requests for the data location to a side file. The new data is then written in the side file and a housekeeping operation reconciles the old and new data locations.
摘要:
A method is described which provides various new data storage system capabilities by using data storage structures within industry standard (or other pre-existing) formats used with data recording devices employing removable media. The data storage structures used by the present method comprise formats which contain regions previously marked as "contents of this region are not of interest" or marked as "no data was recorded within this region". These data storage structures are thus transparent to present data recording devices so as not to disrupt their data processing functions. However, the data storage structures are available to be used by new data recording devices (or old devices that have been updated) so that new data embedded therein may be used to enhance the functionality of the system which utilizes the data storage structures. The types of embedded data may include ECC (error correction codes), tape position information, audit information, security information, mount history, media defect history, authentication notation, generation-identification notation, etc.
摘要:
The control software and hardware in the tape drive control unit creates and manages a header segment at the beginning of the magnetic tape. This header is interposed between a leader portion of the magnetic tape on the 3480-type cartridge and the remainder of the magnetic tape contained therein. This header segment contains two sections, a first of which is a data record directory that is used by the control unit to denote the location of each data record written on to the magnetic tape as well as administrative information associated with the data record. The second section of the header is an administrative information section that contains data relating to the magnetic tape itself. The stream of data records is divided into data segments, a plurality of which comprise a single helical scan track. The helical scan tracks are formed into scan groups and written on the magnetic tape. At least one longitudinal track is written on the magnetic tape coextensive with the helical scan groups to provide data to enable the tape drive to quickly locate data records recorded on the magnetic tape.
摘要:
The use of a dynamically mapped virtual memory system permits the storage of data so that each data record occupies only the physical space required for the data. Furthermore, the data storage subsystem manages the allocation of physical space on the disk drives and does not rely on the file extent defined in the count key data format. Data compaction apparatus is provided to remove the gaps contained in the stream of count key data records received from the host processor. A data compression algorithm is then used to compress the received data into a compressed format for storage on the disk drives. It is the compacted, compressed data that is finally stored on the disk drives. Furthermore, any data record received from the host processor absent data in the user data field therein is simply listed in the virtual memory map as a null field occupying no physical space on the disk drives. The data storage control, through its mapping capability, stores the actual data in the minimum physical space required by overcoming the limitations imposed on large form factor disk drives by the use of count key data format data records. However, the data storage subsystem returns this stored data to the host processor in count key data format through a data record reformatting process once the stored compacted compressed data is staged to the cache memory for access by the host processor. The data storage subsystem is operationally independent of the host processor, yet performs as if it were a standard operationally dependent large form factor disk subsystem.
摘要:
The parallel disk drive array data storage subsystem dynamically maps between virtual and physical data storage devices and schedules the writing of data to these devices. The data storage subsystem functions as a conventional large form factor disk drive memory, using an array of redundancy groups, each containing N+M disk drives. The data storage subsystem does not modify data stored in a redundancy group but simply writes the modified data as a new record in available memory space on another redundancy group. The original data is flagged as obsolete. A mapping table is maintained to identify portions of these redundancy groups which contain newly written or modified virtual track instances. These marked virtual track instances are written to backup medium as a background process and the mapping table is updated to clear the flags that identify these virtual track instances as having been modified.
摘要:
A disk storage system that writes multiple copies of records directed to user-specified volumes. A plurality of spaced apart control units interconnected by direct data links and a corresponding plurality of sets of recording means communicate over the direct data links when a write request is received by one control unit to cause one volume in each set of recording means to write a copy of the received record.
摘要:
A drawer slide for coupling a drawer to a cabinet includes an intermediate rail partially housed within the drawer rail and web and first and second legs which are connected to the web. A flange extends from the first leg toward the second leg. Bearings housed in bearing cages placed between the rails allow sliding movement therebetween. A cabinet rail partially housed within the intermediate rail includes an upright wall and a flange extending away from the upright wall and toward the first leg. Ball and roller bearings housed in bearing cages couple the flanges. Grooves in the flanges are engaged by the ball bearings. Roller bearings housed in bearing cages couple the web of the intermediate rail and the flange of the cabinet rail, and the second leg of the intermediate rail and the upright wall of the cabinet rail.
摘要:
A guide tab and a multiple member slide incorporating such guide tab are provided. The guide tab is coupled to one slide member of the slide. When actuated, the guide tab activates a latch allowing another slide member of the slide to decouple from the slide.
摘要:
An apparatus and method for implementing structure level pointers in a data storage system are provided. With the apparatus and method, a compound pointer system is provided in which fixed level pointers are augmented with associated pointers to metadata describing lower level structures. The companion metadata describes these lower level structures in a manner independent of the actual data stored within the lower level structures. With such an enhanced compound pointer system, an instant copy mechanism can process the pointers to the underlying structures and take instant copies of much finer detail. This allows individual records of data to be represented by the pointer system without having the overhead of carrying a pointer to all the individual records. The instant copy mechanism not only copies the fixed level pointers, but resolves the companion pointers to individual subsets of a general granularity for the instances of the instant copy domains.
摘要:
A mechanism is provided for storing self-defining data and mapping elements with either a fixed set of allowed structures or types or with the structures and types determined by rules. Recovery is enhanced by the use of backward and forward pointers between data and mapping elements for the data elements in the order written by the management algorithm. Recovery is also enhanced by the use of companion pointers with metadata. The companion pointers may include pointers to data or mapping elements that are part of the same structural grouping. The metadata may describe the structural grouping. The metadata may also include pointers to the previous and/or next versions of the same elements. Recovery of the data and/or mapping structures is achieved by the reverse application of the management algorithm.