Patent ID: 8132044

Claim:
A computer system comprising: a client configured to convey read and write requests; and a data storage cluster coupled to receive the read and write requests, wherein the data storage cluster comprises a plurality of data storage locations addressable as rows and columns in an array; wherein in response to detecting a failure of a first column, the data storage cluster is configured to: designate a second column as a replacement for the first column; initiate reconstruction of first data stored in the first column; and store reconstructed data corresponding to the first data in the second column; wherein the data storage cluster is further configured to service received read and write requests during said reconstruction, whereby read data is returned to clients responsive to received read requests and/or write data is written to the array responsive to received write requests; and wherein during said reconstruction, the data storage cluster is further configured to store information corresponding to a write request targeted to the second column in a temporary log.