  Existing disk-based database systems largely fall into two categories -- they
either provide very high performance but few guarantees, or expose the
transaction abstraction satisfying the full ACID guarantees at the cost of
lower performance. In this paper, we present an alternative that achieves the
best of both worlds, namely good performance and transactional properties. Our
key observation is that, because of the frequent use of synchronization
primitives, systems with strong durability can hardly utilize the extremely
high parallelism granted by modern storage devices. Thus, we explore the notion
of weakly durable transactions, and discuss how to safely relax durability
without compromising other transactional properties. We present AciKV, a
transactional system whose design is centered around weak durability. AciKV
exposes to users the normal transactional interface, but what sets it apart
from others is a new "persist" primitive that decouples durability from commit.
AciKV is a middle ground between systems that perform fast atomic operations,
and ones that support transactions; this middle ground is useful as it provides
similar performance to the former, while prevents isolation and consistency
anomalies like the latter. Our evaluation using the YCSB benchmark shows that
AciKV, under workloads that involve write requests, exhibits more than two
orders of magnitude higher throughput than existing strongly durable systems.
