MobiDesk: Mobile Virtual Desktop Computing

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MobiDesk Mobile Virtual Desktop Computing
Ricardo A. Baratto, Shaya Potter, Gong Su, and
Jason NiehDepartment of Computer
ScienceColumbia University, New York, NY,
USA(MobiCom 04, ACM)Heeseung Jo(Department
of Computer Science, KAIST)2005-10-27
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Contents

• Introduction
• Overview
• Display virtualization
• Operating system virtualization
• Network virtualization
• Experimental results
• Conclusions

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Introduction

• A mobile virtual desktop computing hosting
  infrastructure
• Similar with the window remote desktop
• Features
• Session migration
• Transparency
• Low overhead

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Overview

• MobiDesk architecture

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Overview

• MobiDesk architecture (contd)
• Layer 7 proxy exposes a single entry point to
  clients
• Users access a completely private and mobile
  environment using a thin-client session viewer
• MobiDesk virtualizes three resources
• Display
• Operating system
• Network

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Overview

• Benefits over current computing
• High-availability and reliable application
  services
• Persistence and continuity of business logic
• Secure, low-cost global access and transparent
  user mobility
• On-demand access to application and computational
  resources
• Bridging the information gap

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Display virtualization

• Display layers
• Application
• Significant amount of application logic
• Computational power on client
• Translating high level commands
• Middleware
• Re-implement substantial display system, such as
  XFree86
• Hardware
• Device driver
• Provide a virtual video device for each session

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Display virtualization

• Virtual video device
• The commands are forwarded over the network to a
  remote client
• All traffic is encrypted using RC4 stream cipher
  algorithm
• Minimize the overhead of client
• For performance
• Server push model for sending display updates
• Shortest-Remaining-Size-First scheduling to
  improve the responsiveness
• Stateless display mechanism for thin clients

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Operating system virtualization

• Private namespace
• The namespace is all virtual operating system
  resources
• Processes
• User information
• Files
• Devices
• Each computing session has its own virtual
  private namespace
• Translate between the sessions virtual resource
  identifiers and the OS resource identifiers

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Operating system virtualization

• Session virtualization layer
• System call interposition
• wrappers around system calls that translate
  virtual names to physical names and prevent
  accesses across the session boundary
• Chroot and file system stacking
• provide each session with its own file system
  namespace

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Network virtualization

• Issues
• Multiple sessions on the same server may run the
  same service
• Ongoing network connections must be preserved
  when a session is migrated from one server to
  another
• All servers on same subnet
• Each session gets an IP address from the DHCP
  server and uses it as an alias on the NIC on the
  attached server
• Gratuitous ARP is used to resolve MAC address
  change when sessions are migrated
• Proxy re-directs traffic to and from aliased
  addresses corresponding to individual sessions

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Network virtualization

• All servers on different subnets
• Cannot migrate an aliased address obtained in one
  subnet to another (INCONSISTENCY)
• Solution use virtual addresses for proxy mapping
  and map these virtual addresses to physical
  (aliased) addresses dynamically at the proxy
• The aliased address may be reused in old subnet,
  confusing the proxy (CONFLICT)
• Solution each session is bound to a different
  virtual NIC at the proxy, and labels in packets
  are used to identify the virtual NIC to which the
  session is bound

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Experimental results

• All tests run on a high-bandwidth network (even
  WAN has 100Mbps bandwidth)

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Experimental results

• OS virtualization overhead is negligible except
  for ioctl and semget/semctl

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Experimental results

• Network virtualization overhead is negligible

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Experimental results

• Display performance of MobiDesk is impressive
  (full motion video)

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Conclusions

• MobiDesk an architecture for centralized hosting
  of desktop computing sessions
• Abstracts three key resources
• Display
• Operating system
• Network
• Low virtualization overhead and Migration of
  computing sessions
• Unique in its ability to play full-motion video
  remotely