Data storage system and method including data and checksum write staging storage
First Claim
1. A data storage system for a data processing system that provides data read and write commands, said data storage system comprising in combination:
- a data storage facility including a plurality of devices in which data from the data processing system is written;
calculating means for calculating checksum data from said data;
a dedicated checksum storage facility in which calculated checksum data is written; and
a write staging storage area shared by said plurality of devices and by said dedicated checksum storage facility in which calculated checksum data and data from the data processing system are stored prior to writing checksum data in said dedicated checksum storage facility.
1 Assignment
0 Petitions
Accused Products
Abstract
An outboard data storage system for a data processing system including a plurality of data DASD'"'"'s and a dedicated checksum DASD. Write commands and checksum data calculated from the write commands are placed in a staging area under the control of an intelligent controller, operating in parallel with the data processing system CPU, that acknowledges execution of write commands as they are staged. The controller blocks data with contiguous addresses into single write commands and queues the write commands in an order corresponding to physical DASD addresses. Fast reads are achieved by executing read commands directly from the staging storage area and DASD writes are reduced by preempting write commands in the staging storage area with new write commands having the same address.
57 Citations
17 Claims
-
1. A data storage system for a data processing system that provides data read and write commands, said data storage system comprising in combination:
-
a data storage facility including a plurality of devices in which data from the data processing system is written; calculating means for calculating checksum data from said data; a dedicated checksum storage facility in which calculated checksum data is written; and a write staging storage area shared by said plurality of devices and by said dedicated checksum storage facility in which calculated checksum data and data from the data processing system are stored prior to writing checksum data in said dedicated checksum storage facility. - View Dependent Claims (2, 3, 4, 5, 15, 16, 17)
-
-
6. A data storage system for a data processing system that provides data read and write commands, said data storage system comprising in combination:
-
a data storage facility including a plurality of devices in which data from the data processing system is written; calculating means for calculating checksum data from said data; a dedicated checksum storage facility in which calculated checksum data is written; a write staging storage area in which calculated checksum data is stored prior to writing checksum data in said dedicated checksum storage facility; and a controller for controlling the data storage system in response to read and write commands, said controller operating in parallel with the data processing system; said controller including queuing means for ordering checksum data in said write staging storage area in an order corresponding to addresses in said dedicated checksum storage facility.
-
-
7. A data storage system for a data processing system that provides data read and write commands, said data storage system comprising in combination:
-
a data storage facility including a plurality of devices in which data from the data processing system is written; calculating means for calculating checksum data from said data; a dedicated checksum storage facility in which calculated checksum data is written; a write staging storage area in which calculated checksum data is stored prior to writing checksum data in said dedicated checksum storage facility; and a controller for controlling the data storage system in response to read and write commands, said controller operating in parallel with the data processing system; said controller including blocking means for combining checksum data having adjacent addresses into single write commands.
-
-
8. A data storage system for a data processing system that provides data read and write commands, said data storage system comprising in combination:
-
a data storage facility including a plurality of devices in which data from the data processing system is written; calculating means for calculating checksum data from said data; a dedicated checksum storage facility in which calculated checksum data is written; a write staging storage area in which calculated checksum data is stored prior to writing checksum data in said dedicated checksum storage facility; and a controller for controlling the data storage system in response to read and write commands, said controller operating in parallel with the data processing system; said controller including write preempt means for replacing write commands in said write staging storage area with newer write commands having the same address.
-
-
9. A data storage system for a data processing system that provides data read and write commands, said data storage system comprising in combination:
-
a data storage facility including a plurality of devices in which data from the data processing system is written; calculating means for calculating checksum data from said data; a dedicated checksum storage facility in which calculated checksum data is written; a write staging storage area in which calculated checksum data is stored prior to writing checksum data in said dedicated checksum storage facility; and a controller for controlling the data storage system in response to read and write commands, said controller operating in parallel with the data processing system; said controller including read command processing means for executing read commands by reading data from said write staging storage area.
-
-
10. A method of storing data in a data processing system comprising the steps of:
-
staging write commands including data and address information by placing them into a common RAM staging area; removing staged write commands from the staging area and writing the data therefrom onto address locations on a plurality of data DASD'"'"'s; calculating checksum data recovery information from data contained in write commands; storing in the common staging area checksum information corresponding to staged write commands; and writing checksum information onto a dedicated checksum DASD. - View Dependent Claims (11, 12, 13, 14)
-
Specification