Post on 19-Jul-2020
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PCs for Mere Mortals
Monica Lam
Stanford University
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PCs
• Hardware: Cheap and fast– $500: 2.6 GHz, 128 MB mem, 40GB disk
• Market penetration– 69% of U.S. households have PCs– 75% of U.S. people using the Internet– 24% of U.S. households have DSL
� Software� insecure, fragile, frustrating to use
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Internet Worms
• MSBlaster, Nimda, CodeRed , …• Slammer
– infected > 75,000 machines, most within 10 minutes
– damage estimated to be $1 billion
• Patches were available before attacks– Not installed on computers:
at home, companies, Microsoft
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System Management
• Set up– Software purchases and installations– Network of machines– File servers with back up– Firewalls
• Maintenance: – Security patches, software upgrades– Hardware upgrades
• Error recovery– Recover data from back up – Re-install OS + software
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Home Computer Administration Tasks
• Fall on consumers• Cannot solve problems
by simply purchasing new computers!• How much does professional system
admin cost?
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Professional System Admin
• Adminstration and support– $11,900 a PC a year (Gartner)
• Labor costs >> hardware costs • Hidden costs: loss of productivity• A linear function!
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Incremental Improvement Insufficient
• Professional system admin is necessary!– Office users– Telecommuters– Consumers
• Must make system administration scalescale• Leverage hardware technology
– machine cycles– network bandwidth– storage capacity
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How do we make computers as easy to use as TVs?
• Turn on computer connected to a network• Plug in personal “key” to unlock private
data• Dial to different channels of the latest
software
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No software installation!No operating system re-install!
No computer viruses!Automatic backups
Global access everywhere
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Appliances
• Unix-based PC• Fixed function• Simple and intuitive interface• Guaranteed automatic updates
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+ OS, Applications, Data(bits)
Virtual Appliance
Appliance
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Virtual Appliance Computing Model
VAPRepository
INTERNET
User Data
VAPreceivers
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Appliance Flow
VAPRepository
INTERNET
User Data
VAPreceivers
(1) Publisher stores VAPs
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VAPRepository
INTERNET
User Data
VAPreceivers
Appliance Flow
(2) User logs onto a VAP Receiver
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VAPRepository
INTERNET
User Data
VAPreceivers
Appliance Flow
(3) VAP receiver authenticates user
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VAPRepository
INTERNET
User Data
VAPreceivers
Appliance Flow
(4) VAP receiver gets latest copy of VAP, mounts user data
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VAPRepository
INTERNET
User Data
VAPreceivers
Appliance Flow
(5) VAP receiver runs VAP and writes back user data
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OSes are not run onOSes are not run onbarebone hardwarebarebone hardware
– Rich API– Impossible to perfect– Vulnerable– Who re-installs the OS?
Updates it and backs it up?
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VAP receiver: A Service Plane
• A relatively small trusted computing base• Runs VAPs using a virtual machine
monitor – e.g. VMware GSX / ESX– Runs Linux, Windows software
• Provides service functions:– Transfers, updates, backs up VAPs
All without modification to appliancesAll without modification to appliances
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Advantages
• Security– Up-to-date security patches– Pristine copy with each log in
• Appliance publication model is scalable• User mobility• Simple hardware management
– Anonymous hardware
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Top 4 Questions
4. What if I wish to install a flash plug in? or new software?� Published appliance is a fully-tested superset of most users’ environments
� Use multiple VAPs� Company admins prepare 1 for each role� Distribution of software as VAPs� Install software in separate playpen VAP
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4. What if I wish to install a flash plug in? or new software?
Top 4 Questions
� Limited software selection� Limited interactivity� Application lock-ins� Data privacy: photos? tax returns? email?
� Scattered data
3. Why not just more web applications?
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3. Why not just more web applications?
Top 4 Questions
2. How slow is this model? 2. How slow is this model?
1. How to deploy this?1. How to deploy this?
4. What if I wish to install a flash plug in? or new software?
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VAPs as a Data Type
• VAPs are large!• What is in a VAP? • Operations
– Create– Store– Update– Customize– Transfer– Back up
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A Virtual Appliance
• Contents of the bits on an x86 machines• Program disk
– Default Windows XP: 1.5 GB– Red Hat version 7.2: 1.6 GB
• Data disk– Use CVS or network-mounted files for
sharing
• Suspended memory image (100s MB)
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Virtual Networks of Virtual Appliances
Firewall
DNS LDAP
Plone
Parent Network
• A group appliance
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Updates
Version 0
Diffs = Copy-on-write disks
• New software installation & upgrades– Sizes similar to installer and update
packages– Guaranteed to work
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Customizations = InheritancePublisherupdates
� ��� ��
+ UserParameters
inheritance
��� �� �
� � � � � ��� � � �� � � + UserParameters
inheritance
��� �� �
� � � � � ��� � � �� � �
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Transfer: Moving Memory Image• Move memory image, demand-fetch the
rest– Memory image holds working set– Eliminates boot-up overhead
• Especially significant for Java apps
– “Ballooning” reduces size of state
• Transfers a new memory image in about 10 minutes over DSL link
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Transfer opt: Cache
• Opportunity:– Same appliances used on same machines
• Cache– Immutable appliances simplify caching– Speeds up re-use of similar appliances
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Transfer opt: Portable storage
• USB flash drive: 1.5 GB, $175• Compact flash microdrive: 4 GB, $369• 1.8’’ portable hard disk: 40 GB, $180• 2.5’’ portable hard disk: 60 GB, $125
We can carry our cache with us!We can carry our cache with us!
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Transfer opt: Portable storage
A bootable image of a VAP receiver + a cache• Easy deployment:
– Make any PC our own– Does not change the state of hosting PC
• Universal access:– Access to all VAPs on the network
• Network accelerator: – Fast access to appliances previously used
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USB drives (cont.)
• Automatic storage management– A precharging process
pre-loads drive with popular blocks
• Automatic backup:– Continuously saves data in background– Keychain mostly carries redundant state
• Secure: leaves no trace on host computer
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Collective Prototype
• CVL: a Collective virtual appliance language– Virtual appliance networks– Customization specified as inheritance
• Repository– Naming to keep track of versions
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Collective Prototype (cont.)
• VAP Receiver – Assumes the computer can be connected to
the network using DHCP– 500 MB bootable image
• Knoppix Linux• VMware GSX virtual machine monitor
– Talks to the repository via NFS over SSH
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Preliminary Results
• $4G Microdrive over simulated DSL speeds
• No perceivable difference – editing files– playing MP3
• local / remote music: same interface, no perf diff
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Comparing with a local appliance
-2
0
2
4
6
8
10
12
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Windows 2000Linux Redhat Linux kernel compile
LAN DSL NFS
cachednot
cached cachednot
cached
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Replaces Labor with Technology
Manual labor � processor cycles� network bandwidth � storage
System admin� virtual machines� distributing VAPs over the network� portable storage as a network
accelerator
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Conclusions
• Practical alternative to PC desktop model– Works with all x86 software– Runs on generic x86 PC connected to the
network
• Supports Windows, Linux, … Java machines simultaneously
• Up-to-date systems � better security• Easier-to-use software � more software