Maintaining consistency of storage in a mirrored virtual environment

A method of achieving data consistency in a shared storage accessible by a first and second machine. The method includes, in response to receiving state information of the first machine, configuring the second machine to a mirrored operating state corresponding to an operating state of the first machine, receiving a notification that the first machine will overwrite existing data stored in the shared storage, and, in response to the notification, reading the existing data, storing a copy of existing data in a local storage of the second machine, and sending an acknowledgment to the first machine that the copy has been stored in the local storage, to enable the first machine to overwrite the existing data with newly written data. The method also includes, in response to receiving a failure notification, retrieving the copy of the existing data, overwriting the newly written data with the copy of the existing data.