Abstract
Cloud computing is becoming one of the most used paradigins to deploy highly available and scalable systems. These systems usually demand the management of huge amounts of data, which cannot be solved with traditional nor replicated database systems as we know them. Recent solutions store data in special key-value structures, in an approach that commonly lacks the consistency provided by transactional guarantees, as it is traded for high scalability and availability. In order to ensure consistent access to the information, the use of transactions is required. However, it is well-known that traditional replication protocols do not scale well for a cloud environment. Here we take a look at current proposals to deploy transactional systems in the cloud and we propose a new system aiming at being a step forward in achieving this goal. We proceed to focus on data partitioning and describe the key role it plays in achieving high scalability.

Abstract
Modern storage systems requirements demand flexible, scalable solutions that address diverse concerns such as data reduction, replication, security, and multi-cloud distribution. Existing solutions often provide these guarantees through monolithic implementations, limiting their adaptability to specific application needs. This paper introduces PolyLayer, a multi-interface, composable and multi-backend storage architecture. It builds on the concept of stackable storage architectures and redesigns these to support commonly used user APIs (e.g., POSIX, Key-value, Object store), while providing support for data persistence across multiple storage backends (i.e., on-premises, cloud services, blockchain). We present the first steps towards the design of such architecture, while implementing a proof-of-concept and evaluating it. Our preliminary results show that the design can effectively be used in real-world scenarios where new functionality is added to a storage system with low overhead over the base system. For instance, we show how anti-tampering mechanisms can be added to a traditional relational database without any change to the database itself or the application using it.