EP0040694A2
Expired / Lapsed
EP
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Method and system for cataloging data sets
Assignee: International Business Machines Corp
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Filing: 1981-04-15
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Granted: —
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Expires: 2001-04-15
Abstract
Abstract A data set catalog structure eliminates the requirement for base catalog/data volume synchronization in a multi- processing environment while enabling the operating efficiency directly addressing the data volumes. The catalog is distributed between a keyed sequential base catalog and, on each data volume, an entry sequential volume data set. Catalog information which must be synchronized with application data sets is stored in volume records in the volume data set. The method of the invention operates to use and maintain a data base catalog to open a user data set, the data base catalog including a first keyed data set, and on each volume containing user data sets, a second keyed data set, comprising the steps of searching said first keyed data set for a direct pointer to a first volume record in said second kayed data set; comparing the key of the user data set to be opened with the key of said first volume record; and, if the keys match, opening for access the data set addressed by a direct pointer in said first volume record; if the keys do not match, searching said second keyed data set for a second volume record containing the correct key, updating the direct pointer in said first keyed data set to address said second volume record, and opening for access the user data set addressed by a direct pointer in said second volume record.
Inventors
- 👤 Gregory Maurice Plow
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 12:48
CPC Classifications
G; G06; G06F; G06F16/00; G06F16/90; G06F16/901; G06F16/9017; G06F16/902; Y; Y10; Y10S; Y10S707/00; Y10S707/99951; Y10S707/99952; Y10S707/99953
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
162 words
A method for cataloging user data sets stored on a data. volume to enable opening of a user data set by a central processor having access to the data volume, the method comprising the steps of retrieving from a catalog data set a sphere record associated by key with said data set, fetching from said sphere record a first address to a first volume record in a keyed volume data set residing on said data volume, responsive to said first address, retrieving from said volume data set said first volume record, comparing the key of said first volume record with said data set key, if said keys do not compare equal, key searching said volume data set for the volume record containing the correct key, and updating said sphere record to contain the address of the correct volume record, and building user data set control blocks from data set characteristics contained in the volume record key associated with said user data set.
Claim 2
Independent Claim
162 words
A method for cataloging user data sets stored on a data. volume to enable opening of a user data set by a central processor having access to the data volume, the method comprising the steps of retrieving from a catalog data set a sphere record associated by key with said data set, fetching from said sphere record a first address to a first volume record in a keyed volume data set residing on said data volume, responsive to said first address, retrieving from said volume data set said first volume record, comparing the key of said first volume record with said data set key, if said keys do not compare equal, key searching said volume data set for the volume record containing the correct key, and updating said sphere record to contain the address of the correct volume record, and building user data set control blocks from data set characteristics contained in the volume record key associated with said user data set.
Claim 3
Dependent Claim
86 words
A method according to claim 1, comprising the steps of serializing said catalog data set and said volume data set for write access, allocating space on said data volume for said user data set, generating a volume record to include said key and extent information describing the allocated space, writing the generated volume record into said volume data set, generating a sphere record to include said key and a pointer to said generated volume record, and writing the generated sphere record into said catalog data set.
Claim 4
Dependent Claim
119 words
A method according to claim 2, comprising the steps of serializing said volume data set for write access, allocating additional space on said data volume for said user data set, retrieving from said catalog data set the generated sphere record, responsive to the pointer and, selectively, the key fields of said generated sphere record, retrieving said generated volume record from said volume data set, updating said generated volume record to describe the new allocation of space on said data volume, writing the updated volume record into said volume data set; and, if the updated volume record was written into a different location than said generated volume record, updating the generated sphere record to point to said updated volume record.
Claim 5
Dependent Claim
64 words
A method according to claim 2, comprising the steps of serializing said catalog data set for write access, searching said volume data set to retrieve the volume record containing the key of said user data set; generating a recatalog sphere record to include said key and a pointer to the retrieved volume record, and writing the recatalog sphere record into said catalog data set.
Claim 6
Dependent Claim
88 words
A method according to claim 2, prior to defining said user data set, a volume data set for storing the volume records, comprising the steps of allocating space on said data volume for said volume data set, generating a volume control record, including fields identifying the catalog data set(s) using said volume data set and a control interval space map for recording for each control interval in the volume data set indicia representative of control interval space utilization, and writing said volume data set into said data volume.
Claim 7
Dependent Claim
122 words
A method according to claim 5, comprising the steps of searching said volume control record for the name of the requesting catalog data set associated with a request to write a new volume record and, if not present, inserting the name, searching said volume control record space map for a first control interval with adequate free space for said new volume record, accessing said first control interval to insert said new volume record, updating said free space map to reflect the new space utilization of said first control interval, generating a new sphere record containing the address of said first control interval as a pointer to said new volume record and writing said new sphere record into said requesting catalog data set.
Claim 8
Dependent Claim
110 words
A method according to claim 2, comprising the steps of allocating space on a volume for said catalog data set, generating catalog self-describing volume records including catalog identification and extent information, writing said catalog self-describing volume records into the volume data set, inserting the name of said catalog data set and the addresses of said catalog self-describing volume records into a volume control record within said volume data set, generating a catalog self-describing sphere record containing the name of said catalog data set and address pointers to said self-describing volume records and writing said catalog self-describing sphere record into the space allocated on the volume for the catalog data set.
Claim 9
Dependent Claim
116 words
A method according to claim 7, further for opening said catalog data set when the catalog self-describing sphere record is not available such as when the catalog data set is not in an open state, comprising the steps of searching said volume control record for the name of said catalog data set and fetching the associated address pointers, responsive to said associated address pointers, retrieving from said volume data set, the catalog self-describing volume records, verifying that said associated address pointers are correct and, if not, updating said volume control record with the correct address pointers and opening the catalog data set from data set characteristics and extent information contained in said catalog self-describing volume records.
Claim 10
Dependent Claim
156 words
A method according to claim 7, for operating said central processor, the central processor including at least two central processing units sharing said data volume for one central processing unit to serialize a read operation, the method comprising the steps of maintaining in said catalog self-describing volume record a first time field updated during each write access to said catalog data set to record the time of write access, maintaining in each central processing unit a write access time field updated during each write access by said each central processing unit to said catalog data set to record the time of write access and after serializing a read or write operation by said one central processing unit, comparing said first time field with the write access time field of said one central processing unit, and if they do not correspond, updating catalog control blocks describing said catalog data set and updating the write access time field.
Claim 11
Dependent Claim
45 words
A method according to claim 9, for operating said processor in a multiprocessing environment to serialize a write operation by one central processor comprising the further step of locking said catalog data set and said volume data set against access by the other central processors.
Claim 12
Independent Claim
280 words
A system for cataloging user data sets stored on a data volume to enable opening of a user data set by a central processor having access to the data volume and a main storage, said apparatus comprising, means providing a volume data set for storing a plurality of volume records each containing identification information including at least one key field and extent information for user data sets recorded on the data volume, base catalog means for storing a plurality of sphere records, each sphere record containing one or more key fields identifying a user data set and a direct address pointer to a corresponding volume record, means for opening a first user data set having a key name by building, in the main storage, control blocks providing user data set identification and extent information, said means for opening including, means for searching said base catalog means for a first sphere record containing said key name in its key field, means responsive to the direct address pointer stored in said first sphere record for retrieving a first volume record, means for comparing said key name with a first key field of said first volume record, means responsive to a failure of correspondence between said key name and said first key field for searching said volume data set means for a second volume record containing a second key field corresponding to said key name, and for writing into said first sphere record a direct address pointer to said second volume record and means for retrieving information defining the extent of said first user data set from that one of said volume records which contains a key field corresponding to said key name.
Claim 13
Independent Claim
280 words
A system for cataloging user data sets stored on a data volume to enable opening of a user data set by a central processor having access to the data volume and a main storage, said apparatus comprising, means providing a volume data set for storing a plurality of volume records each containing identification information including at least one key field and extent information for user data sets recorded on the data volume, base catalog means for storing a plurality of sphere records, each sphere record containing one or more key fields identifying a user data set and a direct address pointer to a corresponding volume record, means for opening a first user data set having a key name by building, in the main storage, control blocks providing user data set identification and extent information, said means for opening including, means for searching said base catalog means for a first sphere record containing said key name in its key field, means responsive to the direct address pointer stored in said first sphere record for retrieving a first volume record, means for comparing said key name with a first key field of said first volume record, means responsive to a failure of correspondence between said key name and said first key field for searching said volume data set means for a second volume record containing a second key field corresponding to said key name, and for writing into said first sphere record a direct address pointer to said second volume record and means for retrieving information defining the extent of said first user data set from that one of said volume records which contains a key field corresponding to said key name.
Claim 14
Dependent Claim
97 words
A system according to claim 11, self-describing sphere record means stored in said base catalog means for storing direct address pointers to self-describing volume records containing extent information for said base catalog means, volume control record means stored in the volume data set for storing direct address pointers to said self-describing volume records containing extent information for said base catalog means, means for opening said base catalog means, including means responsive selectively to said self-describing sphere record means or said volume control record means for accessing said self-describing volume records to obtain the base catalog extent information.
Claim 15
Dependent Claim
76 words
A system according to claim 11, comprising means responsive to a request for defining a first user data set on a data volume for allocating space on said data volume for said volume data set and means for generating and writing into said volume data set a volume control record including fields for identifying related base catalog means and fields for recording indicia representative of the space utilization of control intervals within said volume data set.
Claim 16
Dependent Claim
78 words
A system according to claim 13, further responsive to a request to define a user data set for generating associated sphere record and volume records, the means for generating including means for searching said volume control record for an addressable control interval with sufficient space for said associated volume record, means for writing said associated volume record into said addressable control interval and means for recording in said associated sphere record the address of said addressable control interval.
References Cited (Backward Citations)
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