Patent ID: 7392425

Claim:
A method for operating a computerized data storage system, comprising: operating a first computer and a second computer, the first computer assigned to a first set of data and the second computer assigned to a second set of data; maintaining two copies of the first set of data, a first copy of the two copies stored on a first set of disks and a second copy of the two copies stored on a second set of disks; maintaining two copies of the second set of data, a first copy of the two copies stored on the first set of disks and a second copy of the two copies stored on the second set of disks; writing, each time that a data is written by the first computer, a label to the first set of disks and to the second set of disks, the label having fields for a status of each computer of the two computers, a first ordinal which is increased each time that a new data is written, and a time stamp giving a time at which the last write was performed; after failure of a computer of the two computers, making, in response to reading the labels of the first set of disks and the second set of disks, a determination by a surviving computer of the two computers as to the most up to date copy of the data assigned to a failed computer of the two computers; and writing a new data to the most up to date copy of the first set of data and the second set of data by the surviving computer.