Data validation system for a group of data storage disks

• US 5,889,934 A
• Filed: 02/24/1997
• Issued: 03/30/1999
• Est. Priority Date: 02/24/1997
• Status: Expired due to Term

• Current Assignee: Data General Corp. (Dell Technologies Inc.)
• Original Assignee: Data General Corp. (Dell Technologies Inc.)
• Inventors: Peterson, Gary S.
• Primary Examiner(s): Ellis, Richard L.
• Application Number:
  US08/805,144
• Time in Patent Office: 764 Days
• Field of Search: 395/182.04, 395/182.05, 395/182.06, 395/182.18, 395/182.19, 371/40.4, 371/40.15, 371/49.1
• US Class Current: 714/6.12
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 2211/104 Metadata, i.e. metadata associated with RAID systems with parity

Abstract

In an array of data storage disks, a data validation system for data arranged in corresponding sectors of a sector group that includes a parity sector. Each user data sector in a sector group is assigned at least two of a plurality of validation fields for placement of a validation stamp. No two data sectors are assigned to identically corresponding sets of validation fields. In the parity sector, there is a parity entry in each of the validation fields created by combining all of the validation stamps in the corresponding validation field throughout the sector group. The validation fields are used to detect partially completed writes into the array of data storage disks.

Claims

1. In an array of data storage disks controlled by at least one I/O processor, said data storage disks having a plurality of user data storage sectors and parity sectors organized by the at least one I/O processor into sector groups, each sector group including one parity sector and no more than a number of user data sectors wherein each of the sectors in the group are located on a different one of said data storage disks, each sector group having an arrangement of data comprising:

a user data field in each of the user data sectors and the parity sector of said sector group;

n validation fields in each of the user data sectors and the parity sector of said sector group, each of the n validation fields having a corresponding validation field in each of the other sectors in said sector group, wherein n is an integer less than the number of user data sectors permitted in said sector group;

each user data sector being assigned at least two of said n validation fields for placement of a validation stamp, wherein no user data sector is assigned to at least two of said n validation fields that correspond identically to the at least two of said n validation fields assigned to any other of said user data sectors in said sector group; and

a parity entry in each of the n validation fields in said parity sector, each parity entry being created by combining all validation stamps found in corresponding validation fields in said sector group.

2. The array of data storage disks of claim 1 wherein the validation stamps are arranged so that when one of the data storage disks having a user data sector in said sector group should fail then all the validation fields in said sector group corresponding to the validation fields having the validation stamps of the failed data storage sector become ineffective and each of the remaining data storage disks in said sector group have at least one validation stamp located in one of the validation fields that remains effective.

3. The array of data storage disks of claim 1 wherein each group of corresponding validation fields in said sector group have about the same number of validation stamps.

4. The array of data storage disks of claim 1 wherein each validation stamp comprises a randomly generated number.

5. The array of data storage disks of claim 1 wherein said parity entry in each of the validation fields is created by XORing all the validation stamps in corresponding validation fields in said sector group.

6. The array of data storage disks of claim 1 wherein the at least two validation fields for placement of a validation stamp in each user data sector are exactly two validation fields.

7. A sector group comprising:

a plurality of user data sectors each located on a different data storage disk in a disk array;

a parity sector on a data storage disk different from the data storage disk of any of the plurality of user data sectors in the sector group;

each of said plurality of user data sectors and said parity sector having a plurality of validation fields that correspond from sector to sector;

each of said plurality of user data sectors having a validation stamp in each of at least two of said plurality of validation fields, wherein no two user data sectors have their respective validation stamps in the same two corresponding validation fields; and

said parity sector having a parity entry in each of the validation fields corresponding to a combination of the corresponding validation fields in the user data sectors of the sector group.

8. The sector group of claim 7 wherein the validation stamps are arranged so that when one of the data storage disks in the disk array should fail then all the validation fields in said sector group corresponding to the validation fields having the validation stamps of the failed data storage sector become ineffective and each of the remaining data storage disks in said sector group have at least one validation stamp located in one of the validation fields that remains effective.

9. The sector group of claim 7 wherein each group of corresponding validation fields in said sector group have about the same number of validation stamps.

10. The sector group of claim 7 wherein each validation stamp comprises a randomly generated number.

11. The sector group of claim 7 wherein said parity entry in each of the validation fields is created by XORing all the validation stamps in corresponding validation fields in said sector group.

12. The sector group of claim 7 wherein the at least two validation fields for placement of a validation stamp in each user data sector are exactly two validation fields.

13. A data validation system comprising:

a plurality of data storage devices;

a plurality of user data sectors each located on a different one of said data storage devices;

a parity sector on a data storage device different from the data storage devices of any of the plurality of user data sectors;

each of said plurality of user data sectors and said parity sector having a plurality of validation fields;

means for saving a validation stamp in each of two preassigned validation fields of one of said user data sectors when data is written into said user data sector, wherein the two preassigned validation fields for any of said user data sectors do not coincide with the two preassigned validation fields for any of the other of said user data sectors; and

means for combining corresponding validation fields in the user data sectors to create a parity entry for a corresponding validation field in the parity sector.

14. A method for recording validation data in an array of data storage disks, said data storage disks having a plurality of user data sectors and parity sectors organized into sector groups, each sector group including one parity sector and no more than a number of user data sectors wherein each of the sectors in the group are located on a different one of said data storage disks, said method comprising:

randomly generating a number for use as a validation stamp;

saving the validation stamp in at least two validation fields of a user data sector; and

combining all validation stamps found in validation fields in the same sector group that correspond to the at least two validation fields to determine and store a parity entry in each corresponding validation field in the parity sector of the sector group.

15. The method of claim 14 wherein the parity sector and the plurality of user data sectors in the sector group each has n validation fields where n is an integer less than the number of user data sectors permitted in a sector group.

16. The method of claim 15 further comprising assigning at least two of said n validation fields to each user data sector for saving validation stamps, wherein no user data sector in a sector group is assigned to at least two of said n validation fields that correspond identically to the at least two of said n validation fields assigned to any other of said user data sectors in said sector group.

17. The method of claim 14 wherein said step of combining comprises XORing all the validation stamps in corresponding validation fields in the same sector group to create the parity entry.

18. A method for recording validation data in an array of data storage disks, said data storage disks having a plurality of user data sectors and parity sectors organized into sector groups, each sector group including one parity sector and wherein each of the sectors in the group are located on a different one of said data storage disks, said method comprising:

saving a validation stamp in m validation fields of a first one of said user data sectors wherein the parity sector and the plurality of user data sectors in the sector group each has n validation fields where m is an integer greater than one and n is an integer greater than m and wherein no user data sector in a sector group has validation stamps in m validation fields that all correspond identically to the m validation fields in which validation stamps are saved in any other of said user data sectors in said sector group; and

combining all validation stamps found in validation fields in the same sector group that correspond to the m validation fields of the first one of said user data sectors to determine and store a parity entry in each corresponding validation field in the parity sector of the sector group.

19. The method of claim 18 wherein said step of combining comprises XORing all the validation stamps in corresponding validation fields in the same sector group to create the parity entry.

20. The method of claim 18 further comprising randomly generating a number for use as the validation stamp.