File storage system and file management method by file storage system

A file storage system comprising a plurality of nodes having a processor and a storage apparatus, the file storage system comprising a first storage system configured to store a file by a distributed file system and perform input/output of the file for a client and a second storage system to which the file stored in the first storage system is transferred, the file storage system implementing a file virtualization function by the first storage system and the second storage system, wherein

• the file storage system has a management information file, which includes a counter value indicating a time-series sequence and which is provided for each file, and an operation log in which operation content of the file is described together with the counter value, and
• the first storage system is configured to:
• perform an operation of the file stored in the first storage system on the basis of an operation request with respect to the file, describe, in the operation log, the counter value of the management information file, associated with the file on which the operation is to be performed, together with the operation content with respect to the file, and reply to the operation request;
• update the counter value of the management information file when the file stored in the first storage system is transferred to the second storage system;
• and wherein,
• when a failure occurs, a relationship among operation content of the operation log, a file stored in the first storage system, and a file stored in the second storage system is identified based on the counter value, and consistency between the file and the management information file is recovered, wherein
• even when the file is deleted from the first storage system in a state where the file is stored in the second storage system, the counter value of the management information file is updated,
• the transfer of the file to the second storage system is migration processing in which the file is transferred but retained in the first storage system, the second storage system having received the transfer is configured to either store the transferred file or update the stored file,
• a deletion of the file from the first storage system is stubbing processing, and recall processing of transferring the deleted file from the second storage system to the first storage system can be performed,
• the management information file has a state of the file of the first storage system that corresponds to the file of the second storage system,
• when an operation with respect to the file of the first storage system is performed, the state of the file is updated,
• when recovering the consistency, the processor is configured to:
• recover the consistency on the assumption that the partial state is Dirty when an update of the file is included in operation content of the file of which counter value is maximum,
• recover the consistency of the management information file on the assumption that the partial state is Cached when operation content of the file of which counter value is maximum is only migration processing of the file,
• recover the consistency of the management information file on the assumption that the partial state is Stub when operation content of the file of which counter value is maximum is only stubbing processing of the file, and
• the counter value of the management information file associated with the file related to the operation is not updated in an operation of the file while being stored in the first storage system.