Using the Short Stroked Portion of Hard Disk Drives for a Mirrored Copy of Solid State Drives

Abstract

Mechanisms for storing data to a storage system comprising a set of one or more solid state storage devices and a set of non-solid state storage devices are provided. A request to write data to the storage system is received and the data is written to the set of one or more solid state storage devices in response to receiving the request. Moreover, a mirror copy of the data is written to the set of non-solid state storage devices in response to receiving the request. Thus, the non-solid state storage devices serve as a mirror backup copy of the data stored to the solid state storage devices.

1 . A method, in a data processing system, for storing data to a storage system comprising a set of one or more solid state storage devices and a set of non-solid state storage devices, comprising:
 receiving a request to write data to the storage system;   writing the data to the set of one or more solid state storage devices in response to receiving the request; and   writing a mirror copy of the data to the set of non-solid state storage devices in response to receiving the request.   
     
     
         2 . The method of  claim 1 , wherein the set of one or more solid state storage devices comprises a smaller number of solid state storage devices than a number of non-solid state storage devices in the set of non-solid state storage devices. 
     
     
         3 . The method of  claim 1 , wherein the solid state storage devices are solid state drives and the non-solid state storage devices are hard disk drives. 
     
     
         4 . The method of  claim 1 , wherein the mirror copy of the data is written to reserved portions of each of the non-solid state storage devices, and wherein the reserved portion of each non-solid state storage device is a portion of a total storage capacity of the non-solid state storage device that is less than the total storage capacity of the non-solid state storage device. 
     
     
         5 . The method of  claim 4 , wherein the reserved portions of each of the non-solid state storage devices are short stroked portions of the non-solid state storage devices located at an outer diameter of physical disks of the non-solid state storage devices. 
     
     
         6 . The method of  claim 4 , wherein data written to the solid state storage devices is data that is determined to be frequently accessed, and wherein data stored in non-reserved portions of the non-solid state storage devices is data determined to be not frequently accessed. 
     
     
         7 . The method of  claim 1 , wherein writing the data to the set of one or more solid state storage devices comprises striping the data across the set of one or more solid state storage devices, and wherein writing the mirror copy of the data to the set of non-solid state storage devices comprises striping the data across reserved portions of each of the non-solid state storage devices in the set of non-solid state storage devices. 
     
     
         8 . The method of  claim 1 , wherein the set of non-solid state storage devices are configured into ranks of non-solid state storage devices, and wherein striping the data across the reserved portions of each of the non-solid state storage devices comprises striping the data across the ranks of non-solid state storage devices such that each rank of the non-solid state storage devices comprises a portion of the data, and wherein the portion of data for a rank is striped across non-solid state storage devices within the rank. 
     
     
         9 . The method of  claim 4 , wherein a number of non-solid state storage devices in the set of non-solid state storage devices is selected based on a sum of short stroked performance measurements of the non-solid state storage devices and an aggregate capacity of the reserved portions of the non-solid state storage devices. 
     
     
         10 . The method of  claim 1 , wherein a number of non-solid state storage devices in the set of non-solid state storage devices is selected as a number of non-solid state storage devices that provides, in the aggregate, a number of operations per second that is approximately the same as the number of operations per second provided by the set of one or more solid state storage devices. 
     
     
         11 . The method of  claim 1 , wherein the number of non-solid state storage devices in the set of non-solid state storage devices is selected according to a minimum number of non-solid state storage devices being determined based on an aggregate storage capacity of reserved portions of the non-solid state storage devices being equal to or larger than a storage capacity of the set of one or more solid state storage devices. 
     
     
         12 . The method of  claim 6 , further comprising:
 determining whether data stored in the reserved portions of the non-solid state storage devices is no longer frequently accessed; and   migrating data stored in the reserved portions of the non-solid state storage devices that is determined to be no longer frequently accessed to the non-reserved portions of the non-solid state storage devices.   
     
     
         13 . A computer program product comprising a computer readable storage medium having a computer readable program stored therein, wherein the computer readable program, when executed on a computing device, causes the computing device to:
 receive a request to write data to a storage system;   write the data to a set of one or more solid state storage devices of the storage system in response to receiving the request; and   write a mirror copy of the data to a set of non-solid state storage devices of the storage system in response to receiving the request.   
     
     
         14 . The computer program product of  claim 13 , wherein writing the data to the set of one or more solid state storage devices comprises striping the data across the set of one or more solid state storage devices, and wherein writing the mirror copy of the data to the set of non-solid state storage devices comprises striping the data across reserved portions of each of the non-solid state storage devices in the set of non-solid state storage devices. 
     
     
         15 . The computer program product of  claim 13 , wherein data written to the solid state storage devices is data that is determined to be frequently accessed, data stored in non-reserved portions of the non-solid state storage devices is data determined to be not frequently accessed, and wherein the computer readable program further causes the computing device to:
 determine whether data stored in the reserved portions of the non-solid state storage devices is no longer frequently accessed; and   migrate data stored in the reserved portions of the non-solid state storage devices that is determined to be no longer frequently accessed to the non-reserved portions of the non-solid state storage devices.   
     
     
         16 . An apparatus, comprising:
 a processor; and   a memory coupled to the processor, wherein the memory comprises instructions which, when executed by the processor, cause the processor to:   receive a request to write data to a storage system;   write the data to a set of one or more solid state storage devices of the storage system in response to receiving the request; and   write a mirror copy of the data to a set of non-solid state storage devices of the storage system in response to receiving the request.   
     
     
         17 . The apparatus of  claim 16 , wherein the processor writes the data to the set of one or more solid state storage devices by striping the data across the set of one or more solid state storage devices, and wherein the processor writes the mirror copy of the data to the set of non-solid state storage devices by striping the data across reserved portions of each of the non-solid state storage devices in the set of non-solid state storage devices. 
     
     
         18 . The apparatus of  claim 16 , wherein data written to the solid state storage devices is data that is determined to be frequently accessed, data stored in non-reserved portions of the non-solid state storage devices is data determined to be not frequently accessed, and wherein the instructions further cause the processor to:
 determine whether data stored in the reserved portions of the non-solid state storage devices is no longer frequently accessed; and   migrate data stored in the reserved portions of the non-solid state storage devices that is determined to be no longer frequently accessed to the non-reserved portions of the non-solid state storage devices.   
     
     
         19 . A system, comprising:
 a set of one or more solid state storage devices;   a set of non-solid state storage devices; and   a controller coupled to the set of one or more solid state storage devices and the set of non-solid state storage devices, wherein the controller is configured to:   receive a request to write data to the storage system;   write the data to the set of one or more solid state storage devices in response to receiving the request; and   write a mirror copy of the data to the set of non-solid state storage devices in response to receiving the request.   
     
     
         20 . The system of  claim 19 , wherein the mirror copy of the data is written to reserved portions of each of the non-solid state storage devices, and wherein the reserved portion of each non-solid state storage device is a portion of a total storage capacity of the non-solid state storage device that is less than the total storage capacity of the non-solid state storage device. 
     
     
         21 . The system of  claim 20 , wherein the reserved portions of each of the non-solid state storage devices are short stroked portions of the non-solid state storage devices located at an outer diameter of physical disks of the non-solid state storage devices. 
     
     
         22 . The system of  claim 21 , wherein data written to the solid state storage devices is data that is determined to be frequently accessed, and wherein data stored in non-reserved portions of the non-solid state storage devices is data determined to be not frequently accessed. 
     
     
         23 . The system of  claim 19 , wherein writing the data to the set of one or more solid state storage devices comprises striping the data across the set of one or more solid state storage devices, and wherein writing the mirror copy of the data to the set of non-solid state storage devices comprises striping the data across reserved portions of each of the non-solid state storage devices in the set of non-solid state storage devices. 
     
     
         24 . The system of  claim 19 , wherein the set of non-solid state storage devices are configured into ranks of non-solid state storage devices, and wherein striping the data across the reserved portions of each of the non-solid state storage devices comprises striping the data across the ranks of non-solid state storage devices such that each rank of the non-solid state storage devices comprises a portion of the data, and wherein the portion of data for a rank is striped across non-solid state storage devices within the rank. 
     
     
         25 . The system of  claim 19 , wherein a number of non-solid state storage devices in the set of non-solid state storage devices is selected as a number of non-solid state storage devices that provides, in the aggregate, a number of operations per second that is approximately the same as the number of operations per second provided by the set of one or more solid state storage devices.