Citation Oggier, F., & Datta, A. (2015). On repairing erasure coded data in an active-passive mixed storage network. International journal on information and coding theory, 3(1). Abstract: A major change has been recently witnessed in networked distributed storage systems (NDSS), with increased use of erasure codes in lieu of replication for realizing data redundancy. Yet, both the industry and academic research communities are still trying to derive most advantage from the trade-offs between storage overhead and reliability that erasure codes provide, while optimizing them to satisfy specific storage needs like repairability and better degraded read performance. Many newly proposed coding strategies for NDSS exploit the storage nodes' computational ability to improve on repairability by applying network coding techniques. However, not every storage node in a NDSS is necessarily endowed with computing capability. This paper studies the effects of passive nodes, i.e., without computational ability, on the repairability of erasure coded data, and how they may impair the promised performance of novel coding techniques. In particular, we provide a lower bound on the minimum storage overhead needed, which could be used as a guideline to evaluate the price to pay in storage overhead to achieve bandwidth efficient repairability when combining passive nodes with erasure coding techniques.