Ravello Labs provides a solution called HVX that allows users to build a private cloud using public cloud infrastructure in an elastic way. HVX is a nested hypervisor that can run on any public cloud and supports running unmodified guest VMs. It implements its own virtual hardware and allows an OpenStack deployment to manage a private cloud consisting of OpenStack compute nodes running as VMs on public clouds. This provides an elastic private cloud that can scale on demand across different public cloud providers without being locked into a single one.

1. Ravello Labs
Virtualizing the cloud
Alex Fishman, 05.27.13
http://www.ravellosystems.com

2. Challenge
How to build a truly
elastic private cloud?

3. Strategies for building a private cloud
➜ Build a data center to accommodate peaks
› Expensive to build and maintain
› Not efficient because of resource under-utilization
› Not truly elastic
➜ VPC on a public cloud (Amazon VPC, Rackspace private
cloud)
› Can’t run original VM images
› Network configuration is limited
› Lock in to a specific provider
› Perceptually less secure
➜ Build a hybrid cloud
› Mostly a hype at this moment
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4. How to achieve elasticity
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The only way to build a truly elastic
private cloud is to utilize public
cloud infrastructure

5. Challenges of using public cloud
➜ Incompatible APIs
› EC2, OpenStack flavors, Azure
➜ Different virtualization technologies
› PV vs HVM
› Virtual HW exposed to VM
➜ Network topology
› Vary from provider to provider
› Often rigid and inflexible
➜ Storage
› Incompatible solutions
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6. Imagine an OpenStack managing a private cloud built
on top of public cloud infrastructure…
➜ Building blocks of our
OpenStack private cloud
› OpenStack compute nodes
on public cloud VMs
› Quantum L2 overlay on
top of a cloud provider’s
network
› Abstraction for Cinder,
Glance and Swift
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Sounds easy… But how do you run an OpenStack
compute node on top of a VM?
Public Cloud A Public Cloud B
Compute nodes Compute nodes
Network and Storage

7. The answer: nested virtualization
➜ HVX is a high performance
nested hypervisor
› Can run on top of any hypervisor
› Runs unmodified guest VMs
› Supports PV and HVM for bottom
virtualization layer
➜ Implements its own set of
virtual hardware
› Compatible with KVM, ESX, XEN
HVX architecture
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Unmodified guest
VM
Guest VM
hardware
HVX hypervisor
Linux
Cloud VM
hardware
Cloud VM

8. HVX highlights
➜ High performance
› Benchmarks were run
with Phoronix test
suite
➜ Advanced memory
management
› Allows cpu/memory
overcommit by
utilizing KSM (page
sharing) and swap
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9. HVX implementation details
➜ Employs binary translation technique
› Translates guest binary code into platform
compatible code
› 32bit guest into 64 bit host
› Replaces privileged instructions
› CPU registers are shadowed
➜ Performance optimizations
› Translated code is cached and chained
› Fast shadow MMU implementation
› Direct execution or user space code (Ring 3)
› PV device implementation for fast IO
› Fast context switching between guest and host kernel
› Uses Linux for guest CPU scheduling and memory
management
➜ Memory protection and data isolation
› Each guest runs in its own context and cannot access
hvx or host memory
› Guest resource usage (CPU/IO) can be throttled if
needed
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..
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Instruction
Instruction
Instruction
….
Jump to next
Tc Instruction
Tc Instruction
Tc Instruction
….
Jump to HVX
Original guest code Translated guest code
Next:
Instruction
Instruction
Instruction
….
Instruction
Next TC:
Tc Instruction
Tc Instruction
Tc Instruction
….
Jump to HVX
HVX compiles next
code section
• HVX reads and compiles a guest
code section. It then gets executed.
• At the end of each translated code
section there is a jump back to HVX
and the process repeats

10. Combining OpenStack with HVX
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Build a fully elastic “virtual” private
cloud built on top of any public
cloud provider
Added bonus: get a truly hybrid cloud by adding
compute nodes that run on top of “real” hardware in a
private data center

11. Use cases
➜ Cost savings for existing cloud users
› EC2 cr1.8xlarge: 244GB, 32 vcpus – $3.5 per hour. When
running 100 VMs: 0.035$ per VM per hour.
➜ Dev/Test
› Deploy and provision a “virtual” private data center in a
matter of minutes
➜ DR
› Migrate easily between clouds
➜ Cloud burst:
› Add a new hardware when demand for computing
capacity spikes
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12. OpenStack demo
➜ Configuration:
› EC2 VM running a management node
› EC2 VM (m3.4xlarge, 4 cpus, 16GB ram) as a compute
node 1
› HPCloud VM (4 cpus, 16 Gb RAM) as a compute node 2
➜ Live migration of a guest VM running on HPCloud
compute node to EC2 compute node
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