| Last Modified On : | March 25, 2008 12:40 PM PDT |
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Develop usage models in order to obtain the advantages of Intel® Virtualization Technology. Classic benefits of virtualization include improved utilization, manageability, and reliability of mainframe systems. Several users with differing OS requirements can more easily share a virtualized server, OS upgrades can be staged across VMs to minimize downtime, and failures in guest software can be isolated to the VMs in which they occur.
While these benefits have traditionally been considered valuable in high-end server systems, the benefits of virtualization also have wider appeal across a broad range of both server and client systems.
Plan virtualization usages in three categories: workload isolation, workload consolidation, and workload migration. The following diagram illustrates these three categories of functional capabilities that encompass a broad range of virtualization usages:
Workload isolation. Virtualization can improve overall system security and reliability by isolating multiple software stacks in their own VMs. Security may be improved because intrusions can be confined to the VM in which they occur, while reliability can be enhanced because software failures in one VM do not affect the other VMs.
Thomas Bressoud and Fred Schneider examined the application of virtualization techniques to achieve system fault tolerance by running identical copies of the same workload in two separate VMs to recover from system failures.1 The Terra2 and ReVirt3 projects are recent academic explorations into the use of virtualization for improved security. Principles of system-software isolation feature prominently in Microsoft’s NGSCB (Next-Generation Secure Computing Base)4 and in VMware’s ACE (Assured Computing Environment).
Workload consolidation. Corporate data centers are challenged by the proliferation of large numbers of heterogeneous and underutilized servers that run single-OS and single-application workloads — for example, Web hosting or file serving. Virtualization makes it possible to consolidate individual workloads onto a single physical platform, reducing the total cost of ownership.
Management of upgrades presents another concern for information technology managers. When new hardware or a new OS release becomes available, the challenges of supporting incompatible legacy software often gate entire corporate upgrades. Virtualization mitigates this problem by allowing systems to run legacy and new operating systems concurrently.
Embedding certain system-management functions within a VM can improve client manageability. For example, routing all network traffic through a management VM can provide network “circuit breaker” capabilities that disconnect the client from a corporate intranet if it appears to be infected by a virus.
Workload migration. By encapsulating a guest’s state within a VM, virtualization makes it possible to decouple the guest from the hardware on which it is currently running and to migrate it to a different platform.
In addition to facilitating hardware maintenance operations, VM migration can be triggered automatically by workload balancing or failure-prediction agents. This capability delivers improved quality of service at a lower operational cost. Xen5 and the Internet Suspend-Resume Project6 have demonstrated workload migration in both servers and clients, and the technology forms the basis of commercial products such as VMotion* from VMware.7
Intel Virtualization Technology
1 T.C. Bressoud and F.B. Schneider, “Hypervisor-Based Fault Tolerance,” Proc. 15th ACM Symp. Operating Systems Principles, ACM Press, 1995, pp. 1-11.
2 G.W. Dunlap et al., “ReVirt: Enabling Intrusion Analysis through Virtual-Machine Logging and Replay,” Proc. 5th Symp. Operating Systems Design and Implementation, Usenix, 2002, pp. 211-224.
3 T. Garfinkel et al., “Terra: A Virtual Machine-Based Platform for Trusted Computing,” Proc. 19th ACM Symp. Operating Systems Principles, ACM Press, 2003, pp. 193-206.
4 P.B. England et al., “A Trusted Open Platform,” Computer, July 2003, pp. 55-62.
5 2. P. Barham et al., “Xen and the Art of Virtualization,” Proc. 19th ACM Symp. Operating Systems Principles, ACM Press, 2003, pp. 164-177.
6 10. M. Kozuch and M. Satyanarayanan, “Internet Suspend/Resume,” Proc. 4th IEEE Workshop Mobile Computing Systems and Applications, IEEE Press, 2002, p. 40.
7 VMware Inc., “Building Virtual Infrastructure with VMware VirtualCenter,” white paper V00014-20001205, 2004; www.vmware.com/pdf/vi_wp.pdf.
