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2600hz Virtualization Expert Q and A

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2600hz Expert Q&A covering Virtualization.

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2600hz Virtualization Expert Q and A

  1. 1. Powerful, Distributed, API CommunicationsCall-in Number: 805-309-5900 Pin 705-705- 141 Expert Q&A: Virtualization Edition April 26th, 2013
  2. 2. Welcome
  3. 3. Our PanelistsAdam Kalsey Chris Spearman Darren Schreiber Voxeo Labs, PSSC Labs, Big Founder, 2600hzTropo Product Data Systems Mgr Architect
  4. 4. Could it all be so simple?
  5. 5. In VoIP, It’s all about Timing
  6. 6. Because virtual machines work by time-sharing hostphysical hardware, they cannot exactly duplicate thetiming activity of physical machines. VMware® virtualmachines use several techniques to minimize andconceal differences in timing performance, but thedifferences can still sometimes cause timekeepinginaccuracies and other problems in software runningin a virtual machine. Source: http://www.vmware.com/files/pdf/techpaper/Timekeeping-In-VirtualMachines.pdf
  7. 7. Because virtual machines work by time-sharing hostphysical hardware, they cannot exactlyduplicate the timing activity of physicalmachines. VMware® virtual machines use severaltechniques to minimize and conceal differences intiming performance, but the differences can stillsometimes cause timekeeping inaccuracies and otherproblems in software running in a virtual machine.
  8. 8. Because virtual machines work by time-sharing hostphysical hardware, they cannot exactlyduplicate the timing activity of physicalmachines. VMware® virtual machines use severaltechniques to minimize and conceal differences intiming performance, but the differences can stillsometimes cause timekeeping inaccuraciesand other problems in software running in a virtualmachine.
  9. 9. Some background…
  10. 10. KVM is to VMWare As FreeSWITCH is to Asterisk • KVM (Kernal Virtual Machine) is the open-source equivalent of VMWare. • Released in 2007 as part of Linux 2.6.20 • KVM is playing “catch-up” to VMWare • Almost full feature parity • KVM doesn’t hold your hand as much • VMWare is more abstracted • Less customization to get VMWare boxes up • Better abstraction in VMWare • KVM is leaner than VMWare
  11. 11. Platform Differences• KVM > VMWare for timing• VMWare > KVM for ease of use• VMWare is the most abstracted virtualization software • Easy to use • Lots of overhead (messes with timing)• KVM is less abstracted • Devices are not plug and play • Can’t easily share devices/ports on the same box in different VMs • Lean, mean and fast!
  12. 12. A few quick notes on Hardware Assisted Virtualization• First Introduced by IBM in 1972 for use in the VM/370• VMWare first got x86 chips for virtualization in 2006 • Hardware assisted virtualization is closer to native • Lots of performance benefits (theoretically) • Early Hardware virtualization was actually slower• KVM got later access to virtualization hardware
  13. 13. Timing: Whose Fault is it?• Is it the Host operating system?• Or the Virtualization?VMWare says it’s the host:Many host operating systems do not provide a way forthe virtual machine to request a physical timer interrupt at a precisely specified time.
  14. 14. What causes this?Lost ticks•Timing is kept in ticks • Ticks have a known rate and are used for measuring time•Virtual Machines cannot call the tick command, and try to “catch up”when they miss ticks•This phenomenon is called “lost ticks”•The solution? • In current VMware products, if the backlog of interrupts grows beyond 60 seconds, the virtual machine gives up on catching up, simply setting its record of the backlog to zero.
  15. 15. In current VMware products, if the backlog ofinterrupts grows beyond 60 seconds, thevirtual machine gives up on catching up,simply setting its record of thebacklog to zero.
  16. 16. When can you Virtualize? Sometimes.
  17. 17. WhyVirtualize?Manage lots of Blocks.
  18. 18. Recap• Virtualization introduces overhead• Overhead effects timing• Timing effects latency sensitive applicationsExample???
  19. 19. Microsoft Campusw/ Overhead
  20. 20. NOPE
  21. 21. Latency• Because of overhead• Microsoft Introduced Latency• Which delayed Carbon Neutrality but saved $140,000.Moral: Know the impact of your overhead, in application and operations
  22. 22. QUESTIONS???

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