STORAGE SYSTEM AND STORAGE CONTROL METHOD

1 . A storage system comprising a plurality of storage nodes each including a non-volatile storage device, a storage controller that processes data read and write from and to the storage device, and a volatile memory, wherein the storage controller stores data related to the data write in the memory, among the data stored in the memory, stores data that needs to be non-volatile in the storage device as log data, makes the log data stored in the storage device redundant among a plurality of storage nodes, and performs a recovery process for the log data when a problem arises with log data stored in the storage device of one of the storage nodes.

2 . The storage system according to claim 1 , wherein the plurality of storage nodes makes the data stored in the memory redundant, and if a failure occurs in the storage device of one of the storage nodes, the storage controller of each storage node re-creates the log data from the data stored in a memory of its own node.

3 . The storage system according to claim 1 , wherein when a failure occurs in the storage device of one of the storage nodes, the storage controller of the storage node can acquire the log data stored in the storage devices of other storage nodes to make the log data redundant again.

4 . The storage system according to claim 1 , wherein the plurality of storage nodes includes an active node in an active state and a standby node in a standby state, and the storage controller of the active node stores control information and cache data in a log buffer, creates the log data from control information and cache data in the log buffer, and transfers the control information and cache data in the log buffer to the standby node, and the storage controller of the standby node matches the state of the memory with the active node using the control information and cache data received from the active node and generates the log data using the control information and cache data received from the active node.

5 . The storage system according to claim 4 , wherein the storage controller of the active node determines whether the control information and cache data need to be non-volatile, and stores the control information and cache data that need to be non-volatile in the log buffer.

6 . The storage system according to claim 4 , wherein the storage controller of the active node writes the cache data to the storage device in log units and performs garbage collection to collect free area.

7 . The storage system according to claim 4 , wherein when the log data is lost in any one of the plurality of storage nodes belonging to the same group, all storage nodes belonging to the group store the base image of the control information in the storage device of its own node as at least part of the log data.

8 . The storage system according to claim 1 , wherein the storage controller executes non-volatilization of data stored in the memory when the number of the storage nodes changes.

9 . A storage control method in a storage system including a plurality of storage nodes each including a non-volatile storage device, a storage controller that processes data read and write from and to the storage device, and a volatile memory, wherein the storage controller stores data related to the data write in the memory, stores data that needs to be non-volatile among the data stored in the memory in the storage device as log data, makes the log data stored in the storage device redundant among a plurality of storage nodes, and performs a recovery process for log data when a problem occurs in log data stored in a storage device of one of the storage nodes.