Automatic memory-based vertical elasticity and oversubscription on cloud platforms

Hypervisors and Operating Systems support vertical elasticity techniques such as memory ballooning to dynamically assign the memory of Virtual Machines (VMs). However, current Cloud Management Platforms (CMPs), such as OpenNebula or OpenStack, do not currently support dynamic vertical elasticity. This paper describes a system that integrates with the CMP to provide automatic vertical elasticity to adapt the memory size of the VMs to their current memory consumption, featuring live migration to prevent overload scenarios, without downtime for the VMs. This enables an enhanced VM-per-host consolidation ratio while maintaining the Quality of Service for VMs, since their memory is dynamically increased as necessary. The feasibility of the development is assessed via two case studies based on OpenNebula featuring (i) horizontal and vertical elastic virtual clusters on a production Grid infrastructure and (ii) elastic multi-tenant VMs that run Docker containers coupled with live migration techniques. The results show that memory oversubscription can be integrated on CMPs to deliver automatic memory management without severely impacting the performance of the VMs. This results in a memory management framework for on-premises Clouds that features live migration to safely enable transient oversubscription of physical resources in a CMP. © 2015 Elsevier B.V. All rights reserved.The authors would like to thank the Spanish "Ministerio de Economia y Competitividad" for the project CLUVIEM (TIN2013-44390-R) and the European Commission for the project INDIGO-DataCloud with grant number 653549.Moltó, G.; Caballer Fernández, M.; Alfonso Laguna, CD. (2016). Automatic memory-based vertical elasticity and oversubscription on cloud platforms. Future Generation Computer Systems. 56:1-10. https://doi.org/10.1016/j.future.2015.10.0021105