Method and system for recovering lost data

A disk array controller internal to a disk array system comprising a plurality of disks, and an intrinsic data memory storing the respective intrinsic data of each of the disks, the controller comprising:

• a status data memory storing status data indicating the status of the disk array system;
• a processor causing the disk array system to:
• read intrinsic data from each of the disks when each disk is initialized;
• store in the intrinsic data memory the intrinsic data read from each disk;
• store in status data memory data on an unusable disk;
• store in status data memory data on a disk that has commenced recovery processing;
• determine whether a disk has been replaced prior to startup by comparing the intrinsic data of each of the disks with the contents of intrinsic data memory at startup;
• reproduce the status of each disk immediately prior to startup on the basis of data stored in status data memory;
• and
• determine whether to continue or to cancel recovery processing on the basis of disk connection status and disk status immediately prior to startup.

A disk array controller internal to a disk array system comprising a plurality of disks, and an intrinsic data memory storing the respective intrinsic data of each of the disks, the controller comprising:

• a status data memory storing status data indicating the status of the disk array system;
• and
• a processor controlling the disk array system, comprising:
• means for reading intrinsic data from each of the disks when each disk is initialized;
• means for storing in the intrinsic data memory the intrinsic data read from each disk;
• means for storing in status data memory data on an unusable disk;
• means for storing in status data memory data on a disk that has commenced recovery processing;
• means for determining whether a disk has been replaced prior to startup by comparing the intrinsic data of each disk with the contents of intrinsic data memory at startup;
• means for reproducing the status of each disk immediately prior to startup on the basis of data stored in status data memory;
• and
• means for determining whether to continue or to cancel recovery processing on the basis of disk connection status and disk status immediately prior to startup.

A disk array system, comprising:

• a plurality of physical disks distributing and storing data having parity;
• an intrinsic data memory storing intrinsic data of the physical disks;
• a disk array controller computing a result equal to an Exclusive OR of data sent from a host, and storing said result together with the data by distributing it to the disks;
• a status data memory storing status data indicating the status of the disk array;
• wherein the controller is capable of performing the following operations:
• reading intrinsic data from each of the disks when each disk is initialized;
• storing in intrinsic data memory the intrinsic data read from each disk;
• deeming as unusable a disk that corresponds to the intrinsic data memory when intrinsic data cannot be stored normally in the intrinsic data memory;
• storing in status data memory data on an unusable disk;
• storing in status data memory data on a disk that has commenced recovery processing;
• determining whether a disk has been replaced prior to startup by comparing the intrinsic data of each of the disks with the contents of intrinsic data memory at startup;
• reproducing the status of each disk immediately prior to startup on the basis of data stored in status data memory;
• and
• determining whether to continue or to cancel recovery processing on the basis of disk connection status and disk status immediately prior to startup.

A disk array system, comprising:

• a plurality of physical disks distributing and storing data having parity;
• an intrinsic data memory storing intrinsic data of the physical disks;
• a disk array controller computing asult equal to an Exclusive OR of data sent from a host, and storing said result together with the data by distributing it to the disks;
• a status data memory storing status data indicating the status of the disk array;
• wherein the controller comprises:
• means for reading intrinsic data from each of the disks when each disk is initialized;
• means for storing in intrinsic data memory the intrinsic data read from each disk;
• means for deeming as unusable a disk that corresponds to the intrinsic data memory when intrinsic data cannot be stored normally in the intrinsic data memory;
• means for storing in status data memory data on an unusable disk;
• means for storing in status data memory data on a disk that has commenced recovery processing;
• means for determining whether a disk has been replaced prior to startup by comparing the intrinsic data of each of the disks with the contents of intrinsic data memory at startup;
• means for reproducing the status of each disk immediately prior to startup on the basis of data stored in status data memory;
• and
• means for determining whether to continue or to cancel recovery processing on the basis of disk connection status and disk status immediately prior to startup.

A computer program product stored on a storage medium for controlling a disk array comprising a processor;

• a plurality of physical disks;
• an intrinsic data memory for storing intrinsic data read from the disks;
• an array controller for controlling the disks;
• and a status data memory for storing status data indicating the control status of the array controller;
• wherein the program causes the disk array to:
• read intrinsic data from each of the disks at startup;
• check the connection status of the array controller and disks by comparing intrinsic data read from the disks with intrinsic data stored in memory, thereby determining whether a disk has been replaced;
• and
• determine, in accordance with the connection status of the controller and disks, and the status data stored in status data memory, whether to perform recovery processing for data stored on one of the disks.