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Linear Data Set
A linear data set (LDS) is a type of data set organization used by IBM's VSAM computer data storage system. The LDS has a control interval size of 4096 bytes to 32768 bytes in increments of 4096. A LDS does not have embedded control information, because it does not contain control information, the LDS cannot be accessed as if it contained individual records. Addressing within an LDS is by Relative Byte Address (RBA), which allows it to be used by systems such as IBM Db2 or the Operating system. The benefit of this is that systems such as the OS can access multiple disk spindles and view it as a single storage implementation. The limitations of this, though, is that this does not make this particularly useful to higher level abstraction levels. Data In Virtual (DIV) and Window services provide an alternative method to direct use of VSAM to access an LDS with a CI size of 4096. See also *Key Sequenced Data Set A key-sequenced data set (KSDS) is a type of data set used by IBM's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Set (IBM Mainframe)
In the context of IBM mainframe computers in the S/360 line, a data set (IBM preferred) or dataset is a computer file having a record organization. Use of this term began with, e.g., DOS/360, OS/360, and is still used by their successors, including the current z/OS. Documentation for these systems historically preferred this term rather than '' file''. A data set is typically stored on a direct access storage device (DASD) or magnetic tape, however unit record devices, such as punch card readers, card punches, line printers and page printers can provide input/output (I/O) for a data set (file). Data sets are not unstructured streams of bytes, but rather are organized in various logical record and block structures determined by the DSORG (data set organization), RECFM (record format), and other parameters. These parameters are specified at the time of the data set allocation (creation), for example with Job Control Language DD statements. Within a running program they are store ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VSAM
Virtual Storage Access Method (VSAM) is an IBM DASD file storage access method, first used in the OS/VS1, OS/VS2 Release 1 (SVS) and Release 2 (MVS) operating systems, later used throughout the Multiple Virtual Storage (MVS) architecture and now in z/OS. Originally a record-oriented filesystem, VSAM comprises four data set ''organizations'': key-sequenced (KSDS), relative record (RRDS), entry-sequenced (ESDS) and linear (LDS). The KSDS, RRDS and ESDS organizations contain records, while the LDS organization (added later to VSAM) simply contains a sequence of pages with no intrinsic record structure, for use as a memory-mapped file. Overview An IBM ''Redbook'' named "VSAM PRIMER" (especially when used with the "Virtual Storage Access Method (VSAM) Options for Advanced Applications" manual) explains the concepts needed to make use of VSAM. IBM uses the term ''data set'' in official documentation as a synonym of ''file'', and ''direct access storage device'' (''DASD'') because ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM Db2
Db2 is a family of data management products, including database servers, developed by IBM. It initially supported the relational model, but was extended to support object–relational features and non-relational structures like JSON and XML. The brand name was originally styled as DB/2, then DB2 until 2017 and finally changed to its present form. History Unlike other database vendors, IBM previously produced a platform-specific Db2 product for each of its major operating systems. However, in the 1990s IBM changed track and produced a Db2 common product, designed with a mostly common code base for L-U-W (Linux-Unix-Windows); DB2 for System z and DB2 for IBM i are different. As a result, they use different drivers. DB2 traces its roots back to the beginning of the 1970s when Edgar F. Codd, a researcher working for IBM, described the theory of relational databases, and in June 1970 published the model for data manipulation. In 1974, the IBM San Jose Research center dev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Key Sequenced Data Set
A key-sequenced data set (KSDS) is a type of data set used by IBM's VSAM computer data storage system. Each record in a KSDS data file is embedded with a unique key. A KSDS consists of two parts, the data component and a separate index file known as the index component which allows the system to physically locate the record in the data file by its key value. Together, the data and index components are called a cluster. Records can be accessed randomly or in sequence and can be variable-length. As a VSAM data set, the KSDS data and index components consist of control intervals which are further organized in control areas. As records are added at random to a KSDS, control intervals fill and need to be split into two new control intervals, each new control interval receiving roughly half of the records. Similarly, as the control intervals in a control area are used up, a control area will be split into two new control areas, each new control area receiving roughly half the contr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entry Sequenced Data Set
An entry-sequenced data set (ESDS) is a type of data set used by IBM's VSAM computer data storage system. Records are accessed based on their sequential order, that is, the order in which they were written to the file; which means that accessing a particular record involves searching all the records sequentially until it is located, or by using a relative physical address (''Relative byte address'', RBA), i.e. the number of bytes from the beginning of the file to start reading. Keys may be used to access records in an ESDS by defining an alternate index. See also *Key Sequenced Data Set *Linear Data Set *Relative Record Data Set *Random access Random access (more precisely and more generally called direct access) is the ability to access an arbitrary element of a sequence in equal time or any datum from a population of addressable elements roughly as easily and efficiently as any othe ... References Computer file systems {{Compu-storage-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relative Record Data Set
A relative record data set (RRDS) is a type of data set organization used by IBM's VSAM computer data storage system. Records are accessed based on their ordinal position in the file (''relative record number'', RRN). For example, the desired record to be accessed might be the 42nd record in the file out of 999 total. The concept of RRDS is similar to sequential access method, but it can access with data in random access and dynamic access. Structure An RRDS consists of data records in sequence, with the record number indicating the record's logical position in the data set. A program can access records randomly using this positional number or access records sequentially. But unlike a Key Sequenced Data Set, an RRDS has no keys, so the program cannot access records by key value. See also *Key Sequenced Data Set * Entry Sequenced Data Set *Linear Data Set A linear data set (LDS) is a type of data set organization used by IBM's VSAM computer data storage system. The LDS h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |