Dynamically mapped data storage subsystem having multiple open destage cylinders and method of managing that subsystem

• US 5,581,724 A
• Filed: 05/12/1995
• Issued: 12/03/1996
• Est. Priority Date: 10/19/1992
• Status: Expired due to Term

• Current Assignee: Storage Technology Corp (Oracle Corporation)
• Original Assignee: Storage Technology Corp (Oracle Corporation)
• Inventors: Milligan, Charles A., Rudeseal, George A., Belsan, Jay S.
• Primary Examiner(s): Gossage, Glenn
• Application Number:
  US08/439,665
• Time in Patent Office: 571 Days
• Field of Search: 395/438, 395/439, 395/440, 395/441, 395/600, 395/182.04, 395/182.05, 395/182.03, 395/183.18, 395/488, 395/489, 395/480, 395/497.04, 395/456
• US Class Current: 711/114
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 12/0804 with main memory updating G06F12/0806 takes precedence
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 2211/1009 Cache, i.e. caches used in RAID system with parity
• CPC Class Codes: G06F 2212/312 In storage controller

Abstract

A data storage subsystem dynamically maps a virtual data storage device image presented to associated processors to physical data storage devices used to implement the data storage subsystem. Multiple destage memory elements are concurrently active to increase an aggregate destage data transfer rate and to allow data to be stored on various memory elements appropriate to the type of data contained in each stored virtual object. An open logical cylinder list is used to maintain data integrity among multiple open destage memory elements. Memory elements are also selected to function as archive memory. The data storage subsystem includes a plurality of data storage elements configured into at least two redundancy groups, each redundancy group including n+m of the data storage elements, and a cache memory connected to the redundancy groups and a host processor interface. The data storage subsystem stores data indicative of the amount of available memory space on each of the open logical cylinders and little used data records are migrated or transferred from other memory elements to the archive memory elements to maintain sufficient available memory space.

Claims

1. A data storage subsystem for storing data records for a host processor, which is connected to said data storage subsystem, said data storage subsystem comprising:

a plurality of data storage elements, a number of said data storage elements being configured into a plurality of redundancy groups, each redundancy group including n+m of said plurality of data storage elements, where n and m are both positive integers, with n greater than 1 and m greater than 0 and wherein each redundancy group is divided into a plurality of logical cylinders for storing data;

control unit means comprising;

at least one multipath storage director means for interconnecting said host processor with said data storage subsystem,

cache memory means connected to and interconnecting said at least one multipath storage director means and said redundancy groups;

processor means for maintaining a plurality of said logical cylinders concurrently open to write data from said cache memory means to a selected one of the plurality of concurrently open logical cylinders, wherein said processor is responsive to receipt of data records from said host processor, for selecting, independent of said host processor, available memory space in one of said plurality of concurrently open logical cylinders to store the received data records; and

disk drive manager means for writing the received data records and data redundancy information for the received data records from said cache memory means into the selected available memory space.

2. The data storage subsystem of claim 1 wherein said processor means stores data which lists all of said plurality of concurrently open logical cylinders.

3. The data storage subsystem of claim 1 wherein said processor means stores data indicative of an amount of available memory space in each of said plurality of concurrently open logical cylinders.

4. The data storage subsystem of claim 1 comprising:

wherein said control unit means is responsive to a subsequent receipt of modifications from said host processor to a previously stored data record stored in one of said redundancy groups, for writing, the modified data record in available memory space in one of said plurality of concurrently open logical cylinders; and

said processor means converts memory space used to store said previously stored data record to available memory space.

5. The data storage subsystem of claim 1

wherein said processor means stores data indicative of a correspondence between the received data records and respective redundancy groups in which each of said received data records is stored.

6. The data storage subsystem of claim 1

wherein said processor means reserves at least one of said redundancy groups as archive redundancy groups, which archive redundancy groups are shared in common by all other ones of said redundancy groups.

7. The data storage subsystem of claim 6

wherein said processor means migrates least used data records from said other ones of said redundancy groups to said archive redundancy groups.

8. The data storage subsystem of claim 1 wherein said processor means partitions said redundancy groups into at least two sets, with redundancy groups in said at least two sets having data storage characteristics which are a function of the number of data storage elements in a redundancy group and data storage capacity of said data storage elements in a redundancy group and media type of said data storage elements in a redundancy group.

9. The data storage subsystem of claim 8 wherein said processor means stores data indicative of which of said redundancy groups are assigned to each of said sets.

10. The data storage subsystem of claim 8 wherein said processor means identifies one of said sets as containing redundancy groups whose data storage characteristics match data storage characteristics of said received data records and wherein said data storage subsystem further comprises:

backend channel means, interconnecting said cache memory means and said disk drive manager means, for transmitting said received data record from said cache memory means to the selected one of said plurality of concurrently open logical cylinders in one of the redundancy groups contained in the identified one of said sets.

11. A method of storing data records in redundancy groups in a data storage system which is connected to a host processor via a processor interface and having a plurality of data storage elements for storing data thereon, a number of said data storage elements being configured into at least two redundancy groups, each redundancy group including n+m of said plurality of data storage elements, where n and m are both positive integers with n greater than 1 and m greater than 0, wherein each redundancy group is divided into a plurality of logical cylinders for storing data, and further including a cache memory connected to said processor interface and said redundancy groups, said method comprising the steps of:

maintaining a plurality of said logical cylinders concurrently open to write data from said cache memory to a selected one of the plurality of concurrently open logical cylinders;

selecting, in response to receipt of data records from said host processor, independent of said host processor, available memory space in one of said plurality of concurrently open logical cylinders to store the received data records; and

writing the received data records and data redundancy information for said received data records in the selected available memory space.

12. The method of claim 11 wherein said step of maintaining comprises:

storing data which lists all of said plurality of concurrently open logical cylinders.

13. The method of claim 11 wherein said step of maintaining further comprises:

storing data indicative of an amount of available memory space in each of said plurality of concurrently open logical cylinders.

14. The method of claim 11 further comprising the steps of:

writing in response to a subsequent receipt of modifications from said host processor to a previously stored data record stored in one of said redundancy groups, the modified data record in available memory space in one of said plurality of concurrently open redundancy groups; and

converting memory space used to store said previously stored data record to available memory space.

15. The method of claim 11 further comprising the step of:

maintaining data indicative of a correspondence between the received data records and respective redundancy groups in which each of said received data records is stored.

16. The method of claim 11 further comprising the step of:

reserving at least one of said redundancy groups as archive redundancy groups, which archive redundancy groups are shared in common by all other ones of said redundancy groups.

17. The method of claim 16 further comprising the step of:

migrating least used data records from said other ones of said redundancy groups to said archive redundancy groups.

18. The method of claim 11 further comprising the step of:

partitioning said redundancy groups into at least two sets, with redundancy groups in said at least two sets having data storage characteristics which are a function of the number of data storage elements in a redundancy group and data storage capacity of said data storage elements in a redundancy group and media type of said data storage elements in a redundancy group.

19. The method of claim 18 wherein said step of selecting comprises:

storing partitioning data indicative of which ones of said redundancy groups are assigned to each of said sets during said step of partitioning.

20. The method of claim 19 wherein said step of selecting further comprises:

identifying one of said sets as containing redundancy groups whose data storage characteristics match data storage characteristics of said received data records; and

transmitting said received data records to the selected one of said concurrently open logical cylinders in one of the redundancy groups contained in the identified one of said sets.