Method for data protection in disk array systems

Abstract

A method and a system for implementing the method are disclosed relating to archival storage of information in large numbers of disk units. The reliability of the stored information is checked periodically using data verification operations whose results are saved. These results establish the veracity of the data and enable compliance with various regulatory requirements. The techniques described enable the use of low cost disk drive technology, yet provide high assurance of data veracity. In a typical system, management information storage is provided in which data entries are associated with each of the disk drives to provide information with respect to the condition of the data on that drive and its last verification. The data verification operations are performed on the data during time periods when I/O accesses are not required.

1 . In a storage system having a plurality of disk drives each with stored data, a system for verifying integrity of the stored data comprising: 
 a management information storage having data entries therein associated with the plurality of disk drives, the entries indicating whether data stored in the disk drives have been verified;    a processor coupled to the management information storage and selectively coupleable to ones of the plurality of disk drives for performing verification operations on the data stored therein, and storing the results in the management information storage; and    a controller coupled to the processor to enable changes in verification procedures.    
   
   
       2 . (canceled)  
   
   
       3 . (canceled)  
   
   
       4 . A system for verifying the integrity of the stored data as in  claim 1  wherein the management information storage comprises a table having entries therein related to a mode of operation of the disk drive.  
   
   
       5 . A system for verifying the integrity of the stored data as in  claim 4  wherein the mode comprises an indication of whether the disk drive is on, off, or in a data verification operation.  
   
   
       6 . A system for verifying the integrity of the stored data as in  claim 5  wherein the mode further comprises an indication of time since the disk drive was last in operation.  
   
   
       7 . A system for verifying the integrity of the stored data as in  claim 5  wherein the mode comprises an indication of the extent to which data on the disk drive has been checked.  
   
   
       8 . A system for verifying the integrity of the stored data as in  claim 1  wherein the management information storage maintains a log of all of the data verification performed for each disk drive.  
   
   
       9 . A system for verifying the integrity of the stored data as in  claim 8  wherein the management information storage further includes security to reduce potential tampering with the data entries  
   
   
       10 . In a storage system having a plurality of disk drives each with stored data, a system for assuring the integrity of the stored data comprising: 
 a management information storage having data entries therein associated with the plurality of disk drives, the entries indicating whether data stored in the disk drives have been verified;    a processor coupled to the management information storage and selectively coupleable to ones of the plurality of disk drives for performing verification operations on the data stored therein, and storing the results in the management information storage; and    a controller coupled to the processor for enabling changes in the verification operations.    
   
   
       11 . In a storage system having a plurality of disk drives each with stored data, a method for verifying the integrity of the stored data comprising: 
 performing verification of the stored data at selected times;    storing results of the verification of the stored data in a management information storage having data entries therein associated with the plurality of disk drives, the entries indicating whether data stored in the disk drives have been verified; and    changing the verification operations.    
   
   
       12 . (canceled)  
   
   
       13 . A method as in  claim 11  wherein the step of storing results further comprises storing the results in a table having entries therein related to a mode of operation of the disk drive.  
   
   
       14 . A method as in  claim 13  wherein the mode comprises an indication of whether the disk drive is on, off, or in a data verification operation.  
   
   
       15 . A method as in  claim 13  wherein the mode further comprises an indication of time since the disk drive was last in operation.  
   
   
       16 . A method as in  claim 13  wherein the mode comprises an indication of the extent to which data on the disk drive has been checked.  
   
   
       17 . A method as in  claim 11  wherein the step of storing further comprises storing a log of all of the data verification performed for each disk drive.  
   
   
       18 . In a storage system having a plurality of disk drives each with stored data, a method for verifying the integrity of the stored data comprising: 
 performing verification operations on the stored data;    storing data entries in a management information storage, the data entries associated with the plurality of disk drives and indicating whether data stored in the disk drives have been verified; and    changing the verification operations.    
   
   
       19 . (canceled)