Compared with numerous static file assignment algorithms proposed in the literature, very few investigations on the dynamic file allocation problem have been accomplished. Moreover, none of them has integrated file replication techniques into file assignment algorithms in a highly dynamic file system where files are created or deleted on the fly and their access patterns varied over time. We argue that file replication and file assignment can act in concert to boost the performance of parallel disk systems. In this paper, we propose a new dynamic file assignment strategy called DORA (dynamic round robin with replication). The advantages of DORA can be attributed to its two main characteristics. First, it takes the dynamic nature of file access patterns into account to adapt to a changing workload condition. Second, it utilizes file replication techniques to complement file assignment schemes so that system performance can be further improved. Experimental results demonstrate that DORA performs consistently better than existing algorithms.