Virtualization Abdullah Aldhamin June 3, 2013
Outline • Virtualization: what and why? • Server Virtualization Offerings • Shortcoming and Challenges on SV • Sustaining Performance while Virtualizing • Future Perspective on SV • Data Center Network Virtualization, what and why? • Overview of VN Projects and how they compare with each others • Future Perspective on DC Network Virtualization • Conclusions
Virtualization • Virtualization • Techniques, methods, approaches to create a virtual instance of a computing resource. • Why? • Advances in h/w technologies, e.g. multi-core • H/W optimization • Cloud computing • Economic factors
Server Virtualization • Key features: • Multiple • Isolated
Server Virtualization: Offerings • Improved H/W utilization • Consolidation • VMs are just files • Faster provisioning and deployment • Better availability and BC solutions
Server Virtualization: Offerings • Lower TCO • Longer h/w purchase cycle • Smaller datacenter • Lower maintenance, power, cooling … etc
Server Virtualization: Challenges • Performance: • CPU and Network • Overhead to do virtual-related emulations • A single NIC = shared bandwidth • Not good for I/O bound apps • Propagation delay latency • Storage • Latency • Needs enough physical storage power to support the multiple VMs • Memory • Amount needed for the application
Server Virtualization: Challenges • Scalability • How many VMs can each physical server accommodate? • Asset management • Tracking a dynamic environment • Service management burdens • Security • Malicious access to the hypervisor means you’re screwed up! • Single-point of failure?
Server Virtualizationand Performance: Can we have both?
Virtualization and Performance • Selective virtualization • Direct assignment of physical NICs to VMs • Isolation and and better I/O • Cost for more NICs and cabling • Flexibility constraints
Virtualization and Performance • Firmware-based I/O virtualization • Virtual I/O channels connected to the same NIC • No true isolation, a channel will impact all other channels • H/W-based I/O virtualization • I/O channels are built in the H/W • Vendor-specific NICs
Virtualization and Performance • Consolidation in a shared resource pool • Allocate VMs to a resource pool instead of physical server • Dynamic resource allocation to VMs based on workload • Complexity and poor visibility on how performance is managed • Adds challenges to asset management
Virtualization and Performance • Management tools • Help manage performance, track SLAs and set priorities • Optimize resource allocation • Proactive failure assessment • Advances in processors and memory • Multiple logical CPUs and improved instructions faster comm. between hypervisor and VMs • Integrate I/O memory mgmt and DMA remapping better I/O virtualization
Highlights on SV Trends • Open-source tools • Joint collaboration between server virtualization vendors and processors’ manufacturers • Hardware-based hypervisor • Convergence of server, storage, desktop and apps virtualization.
So… • Server virtualization • Pros and Cons • How can we overcome (or minimize) the impact on performance • Future perspectives
Is this enough? Does it solve everything we want from Virtualization?
Server Virtualization is NOT enough! • No performance isolations • Security • Poor application deployability • Limited management flexibility • No support network innovation
Data Center Network Virtualization • Multiple virtual networks (VNs) on top of physical network. • Challenges • Addressing schemes • Scalability • Failure tolerance • Security • Resource management
Examples of DC Network Topologies • Conventional DC network topology
Examples of DC Network Topologies • Clos topology • Path diversity
Examples of DC Network Topologies • Fat-tree topology K=4
Network Basic Functionalities/Features • Packet forwarding schemes • Bandwidth guarantees • Relative bandwidth sharing • Multipathing techniques
Examples of Virtual Network Proposals/Implementations
Traditional Data Center • Objective: isolation between tenants • Pros: • Uses VLANs to provide means of isolations • Uses commodity switches and popular hypervisors • SPs can have their own L2 & L3 address spaces • Cons: • Imposes scalability concerns
Diverter • Objective: to provide software-based VN solution for packet forwarding • L3 network virtualization to allow tenants control their addresses • Software module VNET on every physical machine • Replaces VM MAC with physical MAC • Special IP scheme (10.tenant.subnet.vm) • Lacking QoS
NetLord • Objective: virtual network designed to provide solution for scalability of tenants, in order to increase resource utilization and revenue • Utilizes L2 and L3 virtualization: L2+L3 encapsulation • Full address-space virtualization • Uses Diverter forwarding • Uses SPAIN multipathing
NetLord • Pros: • Takes advantage of already implemented schemes to provide basic functionalities • Cons • Not all commercial off-the-shelf switches support IP forwarding • Large packet encapsulation results in more drops and fragmentation • No bandwidth guarantee
Oktopus • Issues with multi-tenant data center networks: • Difficult application performance management • Unpredictable network performance decrease app. performance unhappy customers revenue lo$$e$ • Objectives: to design virtual network abstractions and to explore the trade-off between the guarantees offered to tenants, the tenant cost and provider revenue • Key design concept: two virtual network abstractions: • Virtual cluster • Virtual oversubscribed cluster
Oktopus • Cluster
Oktopus • Virtual cluster
Oktopus • Virtual oversubscribed cluster
Oktopus • Pros: • Increases application performance • Flexibility to InP • Balance between higher application performance and lower cost • Cons • Deployability: only for tree-like physical network topologies
Gatekeeper • Objectives: a virtual network to provide bandwidth guarantees, and achieves high bandwidth utilization • Design features: • Scalable in terms of number of VMs • Predictable in terms of network performance • Flexible based on minimum and maximum bandwidth guarantees • Design elements: • Minimum guaranteed rate • Maximum allowed rate for each VM
Gatekeeper • Pros: • Flexible bandwidth guarantees • Cons: • Other performance features are not addressed • Still under development • Scale of experimental evaluation is small
Seawall • Objective: a virtual network to provide bandwidth sharing in a multi-tenant data center network
Seawall • Pros: • Policy enforcement so no one tenant can consume all bandwidth • Dynamic nature allows for tenant requirement change adjustment • Cons: • Deployability: currently for Windows and Hyper-V
Highlights on Research Direction • Virtualized Edge Data Center: concerned about placement of small data centers at the edge of the network to be closer to end-users • Benefits: • Better QoS for delay sensitive applications • Reduces network communication cost by reducing network traffic across network providers • Lower construction cost compared to large remote data centers • Challenges: • Service placement problem: finding optimal trade-off between performance and construction cost • How to efficiently manage services hosted in multiple data centers?
Highlights on Research Direction • Virtual data center embedding algorithms: to accommodate a high number of VDCs in data centers • Dependent on how efficient virtual resources are mapped to physical ones • Challenges: • Need to consider all physical resources, in addition to servers • Dynamic nature of the demand for data center applications • Energy efficiency: how to optimize the placement of VMs and VNs for energy efficiency?
Highlights on Research Direction • Network performance guarantees: • The design and implementation for bandwidth allocation schemes • Find a good trade-off between maximizing network utilization and guaranteed network performance • Data center management: • Monitoring • Energy management • Failure detection and handling
Highlights on Research Direction • Security: • Mitigating security vulnerabilities • Monitoring and auditing infrastructure • Support for multi-layer security depending on tenants needs
Conclusions • Server virtualization: what and why? • Techniques to address performance issues related to server virtualization • Datacenter network virtualization: what and why? • Recent virtual network architectures: no ideal project to solve all problems! • Future perspectives on server and network virtualization research: we still have a lot to do…
References • FauziKamoun, “Virtualizing the Datacenter Without Compromising Server Performance”, ACM Ubiquity, Vol 2009, Issue 9. • Md. Faizul Mari, et. al., “Data Center Network Virtualization: A Survey”, in IEEE Communications Surveys & Tutorials, Vol 15, pg. 909-928, Sep 2012. • [online] http://en.wikipedia.org/virtualization “Virtualization”, May 2013. • T. Benson, et. al., “CloudNaaS: A Cloud Networking Platform for Enterprise Applications”, SOCC’11, 2011. • A. Edwards, et.al., “Diverter: A New Approach to Networking Within Virtualized Infrastructures”, WREN’09, 2009. • J. Mudigonda, et. al., “SPAIN:COTS Data-Center Ethernet for Multipathing over Arbitrary Topologies,” in Proceedings ACM USENIX NSDI, April 2010. • J. Mudigonda, et. al., “NetLord: A Scalable Multi-Tenant Network Architecture for Virtualized Datacen- ters,” in Proceedings ACM SIGCOMM, August 2011. • F. Hao, et. al., “Enhancing Dynamic Cloud-based Services using Network Virtualization,” in Proceedings ACM VISA, August 2009.