The LHCb DAQ Upgrade for LHC Run3

In order to optimize the physics reach in the large hadron collider (LHC) Run3, foreseen in the years 2021 and beyond, the LHC beauty experiment collaboration has decided to re-design its detector and the data acquisition system (DAQ). The new detector will operate at the LHC bunch-crossing frequency of 40 MHz without hardware trigger. The implementation of the DAQ and the online event filter farm (EFF) for the software trigger is challenging because of the expected data rate of about 40 Tb/s. At this scale, the DAQ and the EFF can be built at an affordable cost only by using off-the-shelf hardware as much as possible. In order to optimally exploit the fast evolution of technology, we need to choose the system architecture at the last moment. Therefore, it should not have strong dependences on specific technologies. We present here the system architecture, the different implementation options that we are studying along with measurements from these studies, and will explain the decision criteria and technology drivers for choosing the components for the final system.