Embodiments of the present disclosure relate to methods, devices and computer readable mediums for random access procedure. The method comprises transmitting, at a terminal device, a random access request in a random access procedure to a network device; in response to receiving, in the random access procedure, from the network device an uplink grant for the terminal device, determining whether a first size of a first data unit indicated by the uplink grant matches a second size of a second data unit stored in a buffer of the terminal device; in response to determining that the first size mismatches the second size, determining a first part of the second data unit for subsequent transmissions.