1. A method for maintaining data correctness in a Hadoop™ based distributed cluster during a failover, in which an original name node is switched to a backup name node due to failure of the original name node, the distributed cluster having a plurality of data nodes and one or more processors, the method being performed by the one or more processors and comprising: on the backup name node: assuming an active role to become a new active name node, upon detecting that the original name node has failed; flagging all of the plurality of data nodes as untrusted; for each data node among the plurality of data nodes: queuing, instead of issuing, commands intended for a data node until the data node is flagged as trusted, and upon receiving an acknowledgement from the data node acknowledging the assumption of the active role of the backup name node, flagging the data node as trusted; and on a respective data node: receiving a first command with a first transaction number from a first name node; receiving a second command with a second transaction number from a second name node, wherein the second transaction number is greater than the first transaction number; and sending an acknowledgment of an active role to the second name node.