System of database copy operations using a virtual page control table to map log data into physical store order
First Claim
1. A method of producing a duplication of a database having a writing step, in which copy data of said database in an external copy data storage are written over by update log data from an external log data storage, where the update log data was acquired after acquisition of said copy data, the method comprising the steps of:
- (a) defining a virtual storage area which comprises virtual pages which have a one-to-one correspondence to blocks in said external copy data storage, and where the virtual pages are arranged in an order according to physical addresses of said blocks to which they correspond;
(b) defining a control table, which includes control values which have a one-to-one correspondence to said virtual pages, and where a control value of the control values will be set when the update log data is set to a corresponding virtual page;
(c) repeating the substeps of;
(i) reading out the update log data acquired in units of said blocks from said external log data storage;
(ii) checking said control value corresponding to the virtual page which corresponds to one of said blocks of copy data to be replaced by said update log data andwhen the control value has not been set, assigning a real storage for the virtual page and storing said update log data to said real storage assigned thereto, and setting the control value,when the control value has already been set, updating the real storage assigned for the virtual page with said update log data; and
(d) searching said control table in the order of virtual page arrangement and repeating the substep of;
(i) when said control value is set, reading out the update log data in said real storage and writing over said copy data in said external copy data storage with said update log data, and resetting said control value.
1 Assignment
0 Petitions
Accused Products
Abstract
A method for producing a duplication of a database stored in an external storage by writing over copy data of the database with update log data which was acquired after acquisition of the copy data. This method is implemented in a computer system having a virtual storage operating system. The system includes a virtual storage area which is defined as having virtual pages which have a one-to-one correspondence to blocks in an external copy data storage, where the virtual pages are the database copy data is stored and in an order according to physical addresses of the blocks. Each update log data is acquired in units of the blocks. A control table is provided which includes control values which have a one-to-one correspondence to the virtual pages. A control value from the control table is set when the update log data is set to the virtual pages. Repeated operations are made of reading out the update log data from the external log data storage and checking a corresponding control value to see if the control value is set, and setting the control value if it was not set. The control table is then searched in the order of virtual page arrangement and where the control values are set the update log data is read out and is written over the copy data in the external copy data storage. This writing thereby being done in such order that the actuator has a minimal travel distance to a track position of external storage where the copy data is stored.
-
Citations
32 Claims
-
1. A method of producing a duplication of a database having a writing step, in which copy data of said database in an external copy data storage are written over by update log data from an external log data storage, where the update log data was acquired after acquisition of said copy data, the method comprising the steps of:
-
(a) defining a virtual storage area which comprises virtual pages which have a one-to-one correspondence to blocks in said external copy data storage, and where the virtual pages are arranged in an order according to physical addresses of said blocks to which they correspond; (b) defining a control table, which includes control values which have a one-to-one correspondence to said virtual pages, and where a control value of the control values will be set when the update log data is set to a corresponding virtual page; (c) repeating the substeps of; (i) reading out the update log data acquired in units of said blocks from said external log data storage; (ii) checking said control value corresponding to the virtual page which corresponds to one of said blocks of copy data to be replaced by said update log data and when the control value has not been set, assigning a real storage for the virtual page and storing said update log data to said real storage assigned thereto, and setting the control value, when the control value has already been set, updating the real storage assigned for the virtual page with said update log data; and (d) searching said control table in the order of virtual page arrangement and repeating the substep of; (i) when said control value is set, reading out the update log data in said real storage and writing over said copy data in said external copy data storage with said update log data, and resetting said control value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
-
-
24. A method of producing a duplication of a database stored in an external storage to protect against a fault of the database by writing, over whole copy data of the database, differential copy data which is a copy of only an updated portion of the database and update log data acquired after the acquisition of said copy data, the method comprising the steps of:
-
(a) defining a virtual storage area, which comprises virtual pages which have a one-to-one correspondence to blocks in said external storage, and where the virtual pages are arranged in the virtual storage in an order according to physical addresses of the blocks in said external storage to which they correspond; (b) assigning real storage for said differential copy data, to a virtual page corresponding to a block where copy data to be replaced by said particular differential copy data exists, and storing the particular differential copy data in the real storage assigned thereto; (c) defining a control table, which includes control values which have a one-to-one correspondence to said virtual pages, and where a control value of the control values will be set when the update log data is set to a corresponding virtual page; (d) repeating the substeps of; (i) reading out the update log data acquired in units of said blocks from said external log data storage; (ii) checking said control value corresponding to the virtual page which corresponds to one of said blocks of copy data to be replaced by said update log data and when the control value has not been set, assigning real storage, for said update log data, to a virtual page corresponding to a block where copy data to be replaced by said update log data exists, and storing each update log data in the real storage assigned thereto and setting the control value, when the control value has already been set, updating the real storage assigned for the virtual page with said update log data; and (e) searching said control table in the order of virtual page arrangement and repeating the substep of; (i) when said control value is set, reading the differential copy data and the update log data out of the real storages in the order of the virtual page arrangement and writing over the copy data in the external storage, and resetting said control value. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31)
-
-
32. In a database system including an external copy data storage for storing copy data arranged into a plurality of blocks, and an external log data storage for storing update log data used to overwrite the copy data, a method for duplicating a database of the database system, the method comprising the steps of:
-
(a) defining a virtual storage including virtual pages which have a one-to-one correspondence with the copy data blocks; (b) defining a control table, which comprises control values which are in a one-to-one correspondence to the virtual pages and where a control value of the control values when the update log data is set to a corresponding virtual page will be set; (c) repeating the substeps of; (i) reading out the update log data from the external log data storage in an arrangement corresponding to the blocks of copy data and setting the read out update log data to virtual pages in a reordered arrangement such that the update log data is reordered in the virtual storage to correspond to the arrangement of the copy data storage; (ii) checking the control value corresponding to the virtual page which corresponds to one of the blocks of copy data to be replaced by the update log data and when the control value has not been set, assigning sequential real storage for the virtual pages set with the update log data and storing the virtual pages having the update log data to the real storage, and setting the control value; when the control value has already been set, updating the real storage assigned for the virtual page with said update log data; and (d) searching said control table in the order of virtual page arrangement and repeating the substep of; (i) when the control value is set, reading out the update log data from the virtual pages into the real storage and writing over the copy data in a sequence according to the reordered arrangement, and resetting the control value.
-
Specification