Abstract: This paper examines disaggregated data center architectures from the perspective of the applications that would run on these data centers, and challenges the abstractions that have been proposed to date. In particular, we argue that operating systems for disaggregated data centers should not abstract disaggregated hardware resources, such as memory, compute, and storage away from applications, but should instead give them information about, and control over, these resources. To this end, we propose augmenting OSes for disaggregation so as to benefit data transfer in data parallel frameworks and speedup failure recovery in replicated, fault-tolerant applications, as well as discussing some of the implementation challenges.