To date weak scaling tests have been run on two of the largest computers in Australia: Gadi (NCI) and Magnus (Pawsey). Here we present the results of those tests and discuss: Gadi: Weak scaling - SolDB3D Q1 Gadi: Weak scaling - SolDB3D Q2 Magnus: Weak scaling - SolDB3D Q2 - v2.10 vs v2.9 Underworld's Gadi installation is setup as a