Data access method, apparatus and computer program product

1. A method for performing data access to a disk array, wherein the disk array comprises a parity disk and a plurality of data disks, the method comprising:

writing data to the parity disk in the disk array in response to a write request to a failed data disk in the disk array when the disk array is in a degraded state;

setting corresponding degraded storage position information in disk resource mapping information so as to indicate that the data are stored in the parity disk;

calculating parity information for the data in response to the disk array returning to an optimized state; and

storing the parity information in the failed data disk which has been recovered.

2. The method of claim 1 , wherein the disk resource mapping information comprises a plurality of degraded storage position indicators for the plurality of data disks, and wherein the setting corresponding degraded position information in the disk resource mapping information comprises setting in the disk resource mapping information a degraded storage position indicator corresponding to the failed data disk.

3. The method of claim 2 , wherein the setting corresponding degraded storage position information in the disk resource mapping information comprises setting the degraded storage position indicator as a first value indicating that the data are stored in the parity disk.

4. The method of claim 2 , further comprising:

obtaining the corresponding degraded storage position information from the disk resource mapping information in response to a read request to the data when the disk array is in the degraded state; and

obtaining the data from the parity disk according to indication of the corresponding degraded storage position information.

5. The method of claim 2 , further comprising:

obtaining corresponding degraded storage position information from the disk resource mapping information in response to a read request to a data disk in the disk array when the disk array is in an optimized state;

obtaining data from the parity disk when it is determined the corresponding degraded storage position information indicates that the data are stored in the parity disk; and

obtaining data from the data disk when it is determined the corresponding degraded storage position information indicates that the data are not stored in the parity disk.

6. The method of claim 1 , further comprising:

in response to a write request to the data in the optimized state, writing new data to the failed data disk which has been recovered;

writing corresponding parity information to the parity disk; and

setting corresponding degraded storage position information as a second value indicating that the data are not stored in the parity disk.

7. An apparatus for performing data access to a disk array, wherein the disk array comprises a parity disk and a plurality of data disks, the apparatus comprising:

a processor; and

a memory coupled to the processor and having instructions stored therein, the instructions, when executed by the processor, causing the apparatus to perform acts comprising:

writing data to the parity disk in the disk array in response to a write request to a failed data disk in the disk array when the disk array is in a degraded state;

setting corresponding degraded storage position information in disk resource mapping information so as to indicate that the data are stored in the parity disk;

calculating parity information for the data in response to the disk array returning to an optimized state; and

storing the parity information in the failed data disk which has been recovered.

8. The apparatus of claim 7 , wherein the disk resource mapping information comprises a plurality of degraded storage position indicators for the plurality of data disks, and wherein the setting corresponding degraded position information in the disk resource mapping information comprises setting in the disk resource mapping information a degraded storage position indicator corresponding to the failed data disk.

9. The apparatus of claim 8 , wherein the setting corresponding degraded storage position information in the disk resource mapping information comprises setting the degraded storage position indicator as a first value indicating that the data are stored in the parity disk.

10. The apparatus of claim 8 , wherein the acts further comprise:

obtaining the corresponding degraded storage position information from the disk resource mapping information in response to a read request to the data when the disk array is in the degraded state; and

obtaining the data from the parity disk according to indication of the corresponding degraded storage position information.

11. The apparatus of claim 8 , wherein the acts further comprise:

obtaining corresponding degraded storage position information from the disk resource mapping information in response to a read request to a data disk in the disk array when the disk array is in an optimized state;

obtaining data from the parity disk when it is determined the corresponding degraded storage position information indicating that the data are stored in the parity disk; and

obtaining data from the data disk when it is determined the corresponding degraded storage position information indicates that the data are not stored in the parity disk.

12. The apparatus of claim 7 , wherein the acts further comprise:

in response to a write request to the data in the optimized state, writing new data to the failed data disk which has been recovered;

writing corresponding parity information to the parity disk; and

setting corresponding degraded storage position information as a second value indicating that the data are not stored in the parity disk.

13. A computer program product having a non-transitory computer readable medium which stores a set of instructions to perform data access to a disk array, wherein the disk array includes a parity disk and a plurality of data disks; the set of instructions, when carried out by computerized circuitry, causing the computerized circuitry to perform a method of:

writing data to the parity disk in the disk array in response to a write request to a failed data disk in the disk array when the disk array is in a degraded state; and

setting corresponding degraded storage position information in disk resource mapping information so as to indicate that the data are stored in the parity disk,

wherein the disk resource mapping information comprises a plurality of degraded storage position indicators for each of the plurality of data disks, and

wherein the setting corresponding degraded position information in the disk resource mapping information comprises setting in the disk resource mapping information a degraded storage position indicator corresponding to the failed data disk.

14. The computer program product of claim 13 , wherein the method further comprises:

in response to a request to read data, reading the degraded storage position information together with a set of other disk resource mapping information without additional read operations.

15. The computer program product of claim 14 , wherein the disk resource mapping information is stored in a virtual block structure, and wherein reading the degraded storage position information together with a set of other disk resource mapping information without additional read operations includes:

accessing the virtual block structure; and

reading the disk resource mapping information.

16. The computer program product of claim 13 , wherein the method further comprises:

in response to a write request to the plurality of data disks in the disk array, obtaining a corresponding plurality of degraded storage position indicators from the disk resource mapping information;

identifying a set of data disks in the disk array that are not in a failed state by analyzing the corresponding plurality of degraded storage position indicators; and

writing data to the set of data disks in the disk array that are not in a failed state.