The DEPAS (Decentralized Probabilistic Auto-Scaling) algorithm assumes an overlay network of computing nodes where each node probabilistically decides to shut down, allocate one or more other nodes or do nothing. DEPAS was formulated, tested, and theoretically analyzed for the simplified case of homogenous systems. In this paper, we extend DEPAS to heterogeneous systems.
Another decentralized auto-scaling approach was proposed by @cite_7 . They aim to develop a Platform as a Service for hosting sites in the cloud. In their approach, each virtual machine is managed by a VM manager which is connected through a custom overlay network to other VM managers that store instances of the same sites. The utility of a site instance is computed as the ratio between the allocated CPU capacity and the CPU demand. The utility of the system is the minimum utility of all instances of all sites. A decentralized heuristic algorithm is used to maximize the utility of the system while minimizing the cost of adaptation. The resulting system is scalable with respect to the number of virtual machines and the number of sites, but it is not scalable with respect to the number of instances of a site.
@cite_7
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We address the problem of resource management for a large-scale cloud environment that hosts sites. Our contribution centers around outlining a distributed middleware architecture and presenting one of its key elements, a gossip protocol that meets our design goals: fairness of resource allocation with respect to hosted sites, efficient adaptation to load changes and scalability in terms of both the number of machines and sites. We formalize the resource allocation problem as that of dynamically maximizing the cloud utility under CPU and memory constraints. While we can show that an optimal solution without considering memory constraints is straightforward (but not useful), we provide an efficient heuristic solution for the complete problem instead. We evaluate the protocol through simulation and find its performance to be well-aligned with our design goals.