The Dgraph stores the data sets it queries in a set of databases. For high availability, these can be stored on HDFS/MapR-FS or a shared NFS. They can also be stored on the local disk for a non-HA option.
Regardless of where you put your Dgraph databases, you must increase the allowed numbers of open file descriptors and processes on all nodes in the cluster, including Hadoop nodes. For more information, see Increasing the numbers of open file descriptors and processes.