Emc Corporation

Terry Seto Lee

Philip E Tamer

Arieh Don

Alexandr Veprinsky

Xiali He

Michael J Scharland

Narasimha Mandyam Krishnakumar

Neil J O'Brien

Mei Ren

Yiwen Huang

Described are techniques for determining one or more logical data objects for a storage location. The storage location indicating a location on a device of a data storage system is provided. A list of one or more logical data objects is received. For each of the one or more logical data objects, one or more related data storage system locations associated with each logical data object are determined. It is determined whether the storage location is included in any of the one or more logical data objects. It is also identified whether, for each of the one or more logical data objects, the storage location is one of the one or more related data storage system locations associated with each logical data object.

Techniques for determining logical data objects corresponding to physical storage locations

A method for processing a write instruction for writing data to a database stored on a logical device includes obtaining first and second addresses that specify the location of the data in respective first and second address spaces. A third address corresponding to an expected location of the data record in the first address space is then calculated. On the basis of a comparison between the first address and the third address, a determination is made as to whether to execute the write instruction.

Database verification following database write

Described are techniques for processing a data operation. A data operation is received at a data storage system. The data operation requests a modification of data stored in the data storage system. A first address is obtained that represents a starting address of the data operation. A calculation is performed representing a boundary condition of the starting address of the data operation. Based on the calculation, it is determined whether the data operation has a starting address which is properly aligned.

Data operation validation

A method for processing a request from a host to write a database record to a target location on a logical device associated with a data-storage system in data communication with the host includes maintaining, at the data storage system, information identifying extents of the logical device that are designated for storage of database records, and, on the basis of the information, determining whether the target location is one on which a database record is permitted to be stored.

Data verification following database write

Described are techniques for processing data requests in connection with an I/O operation. A write data request is sent from a host to a target data storage system. The host performs a data validation, such as a checksum calculation, using the data of the data request. The data request is sent to the target data storage system. The target data storage system may be enabled to perform data validation processing on a per device basis by setting one or more device flag bits for a device. The target data storage system performs data validation processing in accordance with the flag bit settings of a device associated with a data request. A target checksum value using the data received on the target data storage system is determined and compared to the host checksum value in order to determined data validity. Data recovery processing is performed if data corruption is determined. A partial write of the data requested may be performed for those data portions occurring prior to the corrupted data that have been successfully validated.

Protecting database records against a failed write operation

A method and apparatus for obtaining an identifier of a logical unit of data that belongs to a database. In one embodiment, a method of obtaining a first identifier of a logical unit of data that belongs to a database is described. The first identifier uniquely identifies a location of the logical unit of data within the database, and the method includes determining a group of identifiers that includes the first identifier based upon information, concerning a structure of the database, that does not directly specify the group of identifiers. In one aspect of the present invention wherein the logical unit of data has an application space label which can be used by application programs to access the logical unit of data from the database, the method obtains the first identifier without first accessing the logical unit of data from the database using the application space label.

Method and apparatus for obtaining an identifier for a logical unit of data in a database

A method and apparatus for indenting changes to a logical object on a host computer by examining information relating to a physical level in a data storage system wherein the logical object is stored. In one embodiment, a method for determining changes to a logical object subsequent to a reference time is described for a logical object that belongs to an application layer of a host computer in a computer system. The computer system includes the host computer, a storage system, and at least one mapping layer that maps the logical object to a physical layer relating to physical storage locations on the storage system. The physical layer includes physical change information relating to changes made to the physical storage locations on the storage system subsequent to the reference time. The method includes steps of mapping the logical object from the application layer to the physical layer to identify which physical storage locations include data corresponding to the logical object, examining the physical change information to identify any of the physical storage locations identified in the step of mapping that include data that has changed subsequent to the reference time, and determining that changes have been made to the logical object when any physical storage locations are identified in the step of examining as including data that has changed subsequent to the reference time.

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Arcadia, CA, United States of America

Terry Seto Lee