Design for the distributed data locator service for multi-site data repositories

•Distributed data location informing service considered for multi-site data repository.•Multi-master bi-directional asynchronous replication method between remote databases.•Bi-directional database replication considered for ITER and the REC, and also for LHD and SNET.•Good performance results measured by using the LHD database and SNET.•Bi-directional replication (BDR) as a promising solution for distant international collaborations. The Remote Experimentation Centre (REC) in Japan has been preparing to replicate the full dataset of ITER over 10 000 km distance. In such a multi-site data repository environment, the data location informing service will be essential to find and retrieve the data efficiently. Considering the long latency time and the self sustainability of remote sites, the data location database should be running at each repository site. Multi-master asynchronous replication between cooperating databases will be essential to realize the remote experimental collaborations in fusion research. This study has investigated the functional differences of some relational databases and found that Postgres BDR has the expected database replication capabilities. Bi-directional replication (BDR) tests by using the LHD database and SNET revealed that the throughputs are sufficient for remote collaborations in fusion experiments.