IT departments are doing this to try to find "ways to use the newest in technology (processors, storage, memory, communications, and software) to improve: the application environment by increasing performance; optimizing processor utilization through workload management, scalability and reliability; increasing organizational efficiency by reducing costs of hardware, software and staff; and reducing both the number and the impact of system outages regardless of the underlying reason," said Kusnetzky.
At a recent Gartner Symposium/ITxpo, Gartner Inc. vice president John Enck called virtualization a "megatrend."
"We see virtualization being extremely important across all server types" and "virtualization is the best tool you have right now in the market to increase efficiency and drive up the utilization of your servers," said Enck.
What all this boils down to is that virtualization should make today's more powerful computers more productive while simultaneously making them easier and cheaper to manage.
NOVEMBER 21, 2005 (IDG NEWS SERVICE) - A recent survey of 100 IT executives predicts that IT spending will decrease slightly in 2006 as more businesses worry about global economic conditions, but security software and enterprise IT upgrades remain top concerns.
Macroeconomic factors such as high oil prices and a devastating hurricane season in the U.S. have caused 40% of the executives surveyed by Goldman, Sachs & Co. to consider reducing their 2006 IT budgets, according to survey results released Friday. Most executives, 52%, believe IT spending will be unchanged in 2006.
Security software has been a long-running priority among the executives on Goldman’s survey panel, and nothing has changed that mind-set based on the current results. Spending on antivirus products has eased up after a flurry of activity, but CIOs continue to focus on improving security in areas like identity management and regulatory compliance, the survey said.
Other enterprise software priorities include enterprise resource management and customer relationship management systems, with CIOs upgrading those two categories to top priorities. When Goldman polled its panel in April, ERP and CRM software were considered only medium priorities.
Among enterprise software vendors, VMware Inc. and SAP AG were the two most cited companies receiving a larger percentage of the respondents’ IT budgets. Virtualization technologies are a hot topic this year as Intel Corp. and Advanced Micro Devices Inc. prepare chips that improve the performance of virtualization software . Respondents listed Novell Inc. and Computer Associates International Inc. as receiving less of their IT budgets.
“ With virtual machines of the desktop sort that VW5 enables, PC users can literally carve their desktop and notebook systems into completely separate instances of Windows that run side-by-side with each other as though the other instances don't exist. In other words, if some process in one tries some sort of security exploit like a buffer overflow, it can't get to the others any more than a buffer overflow could affect another computer across the network. It can only get to whatever is running in that instance or "partition of Windows." The idea of partitioning systems in this way makes it possible to dedicate partitions to specific activities. For example, you can do all your Web browsing in one partition while you run your corporate applications in another and your personal applications like Quicken in a third and never the three shall meet. I'm a Firefox user. But for those Web sites that require Internet Explorer (which I'm always nervous about using), I just run it in a separate partition. Using a virtual machine for just one application is like driving on a completely empty road with airbags. “
Intel has announced the arrival of the first desktop chips to include its hardware-based virtualization technology known as VT (codenamed Vanderpool ). This could very well signal a new era in desktop/notebook computing and I would think long and hard before buying a new system that doesn't include this new and worthwhile technology.
So, why is the Intel announcement so significant? Until Intel started releasing its VT technology (it first debuted in the company's recently announced Paxville XEON server chips ), companies like SWSoft, VMWare, and Microsoft had to do a lot of the virtual machine heavy lifting in their software. Without any hardware assistance the likes of which VT provides, it takes far more in the way of physical resources (processor, memory) to launch and run virtual machines than it does if those instantiations can be activated through hardware. While such technologies make it easier for competing virtual machine software solutions like Xen to get in the virtual machine game, Raghu Raghuram, VMware's senior director of strategy and marketing, told me earlier this year that his company welcomes innovations like VT because end users will get better performance and his company can focus its attention on adding value in higher layers of the virtualization stack such as management. VMWare is wasting no time in rolling out its support for Intel's VT technology. According to a press release on its Web site, VT support is being beta tested in version 5.5 of VMWare Workstation, which the company expects to release by the end of the year.
To start out, why don't you describe what your company does? VMware produces virtualization software. What that means is we take a physical x86-based system and we provide the multiple isolated, movable partitions that you can run operating systems with their applications in. In terms of what the customer gets, they get a way to drive utilization from, say, 15 percent, on up to 85 percent. They get very cost-effective ways to do disaster recovery, high availability, provisioning--all sorts of system-level services.
Pick a typical customer. What's their life before and after VMware? What changes? A typical customer has got widely proliferated x86 machines, and depending on the power of the server, they can get a 10-to-1, 4-to-1 reduction in the number of servers they need. Or they can stop that proliferation and contain it better. And beforehand, to bring a new service online you have to go order the machine, install it in the server room, get it network-connected, make sure the power is there--it can be a multi-month process. Post-VMware, all they do is keep pre-built images of different software services like SQL Server, and when someone needs that service, they just find some excess capacity somewhere and deploy it.
So what's the penalty? Why doesn't everybody do this? Actually, what we were finding is that for people who use it, it's become the default way that they run their x86 workloads.
Support for full virtualization never part of x86 design, e.g. certain supervisor instructions would need to be handled by the VMM for correct virtualization, but executing with insufficient privilege fails silently as opposed to a nice trap.
Virtualizating x86 MMU is also a challenge.
VMWare ESX Server dynamically rewrites portions of the hosted machine code to insert traps wherever VMM intervention might be required. Applied to entire guest OS kernel since all non-trapping privileged sintrsuctions must be caught and handled.
ESX maintains shadow versions of things like page tables and maintains consistency with the virtual tables by trapping every update attempt – high cost for update-intensive operations such as creating a new application process.
the architecture provides a software-managed TLB as these can be easily virtualized.
Tagged TLB: ability to associate an address-space identifier tag with each TLB entry to allow hypervisor and each guest OS to efficiently coexists in separate address spaces – no need to flush the entire TLB when transferring execution.
Short for t ranslation l ook-aside b uffer , a table in the processor’s memory that contains information about the pages in memory the processor has accessed recently. The table cross-references a program’s virtual addresses with the corresponding absolute addresses in physical memory that the program has most recently used. The TLB enables faster computing because it allows the address processing to take place independent of the normal address-translation pipeline .
Xen tries to virtualize this with as little overhead as possible.
Harder dues to x86’s use of hardware page tables.
VMWare: provide each guest OS with a virtual page table, not visible to the memory management unit. Hypervisor responsible for trapping accesses to the virtual page table, validating updates, and propagating changes back and forth between it and the MMU-visible “shadow” page table.
Full virtualization forces use of shadow page tables, Xen is not so constrained
Xen only involved in page table updates to prevent guest OSes from making unacceptable changes.
Approach: Register guest OS page tables directly with MMU, and restrict guest OSes to read-only access.
XenoLinux implements a balloon driver, which adjusts a domain’s memory usage by passing memory pages back and forth between Xen and XenoLinux’s page allocator.
Could modify Linux MM routines directly, balloon driver makes adjustments by using existing OS functions, thus simplifying Linux porting effort.
Paravitualization could be used to extend the capabilities of this driver: e.g. out-of-memory handling mechanism in the guest OS can be modified to automatically alleviate memory pressure by requesting more memory from Xen.
All other domains access disk through abstraction of virtual block devices.
Domain0 manages the VBDs – keeps mechanisms in Xen very simple.
VBD comprises a list of extents with associated ownership and access control information.
Guest OS disk scheduling algorithm will reorder requests prior to queueing them on the ring in an attempt to reduce response time or to supply differentiated service.
Xen has more complete knowledge of actual disk layout, so we support reordering within Xen, and responses may come back our of order.
Xen services batches of requests from competing domains in a simple round-robin fashion; these are then passed to a standard elevator scheduler before reaching disk hardware. Domains can pass down reorder barriers to prevent reordering.