Trigger of the magnetic reconnection is considered to be associated with some instabilities associated with the thin current sheet with the thickness of the ion inertial scale. The Cluster satellites confirmed a previous picture of the thinning of cross-tail current sheets in the substorm growth phase and prior to the occurrence of magnetic reconnection. They also show pictures of the temporal variation of the current sheet associated with the current sheet oscillation and temporal formation of the current sheet structure different from the Harris-type current sheet. Using Cluster data in the magnetotail, characteristics of such current sheet reconfiguration prior to magnetic reconnection (occurrence of fast plasma bulk flows) are presented and discussed which type of the structure may be important or not.