What a tangled mess….
Tackling Windows Complexity
Rob Short
Development Manager
Windows NT
Microsoft Corporation
08/12/97
What I’ll talk about
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The problem
Hardware detection/installation issues
Application installation
Managing large installations
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Today’s Situation
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Computers are being used by everyone
>100 Million installed Windows systems
Feedback indicates severe problems
Changes are unpredictable
– add/remove hardware
– add/remove software
• Windows is too hard to manage
– both in single and large environments
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Hardware configuration
• Obvious: This should not be hard
– most systems have less than two dozen devices
– resource allocation is well defined problem
• Reality
– One out of ten attempts to change hardware has
a problem of some sort
– Out of 100 Million users that is 10 Million
people with a problem!!!!!!
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Hardware related issues
• Incredible number and variety of devices
– 4808 different system designs
– 4000 + add in cards
– 1200+ different printers
• Few hardware standards,
– many devices don’t implement the whole spec
– newer devices are better, but people expect
their old systems/devices to work
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Windows NT 4.0 HCL
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Hardware Standards
(oxymoron)
• No standard basic system structures
– AT compatible core in most x86 systems
• required to run DOS or WIN95
• software can, sort of, assume its there
• System buses, implementations are different
– PCI, ISA, EISA, Microchannel,
• Newer standards address SW problems
– PCI, 1394, USB, ACPI, etc
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Windows Driver Model
• Plug and Play and Power Management
device driver interfaces for both flavors of
Windows
• Supports load/unload, start and stop
• Support Plug and Play hardware standards
• Built on existing Windows NT input/output
(I/O) infrastructure
• Separate class and port drivers
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WDM Bus Drivers
• Standard WDM driver that exposes a bus
• “Bus” is any device (virtual or physical) on
which other devices are connected
• Includes enumeration routines
• Responds to new Plug and Play and Power
Management I/O request packets (IRPs)
• Extensible via filter drivers
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Mouse
kbd
Windows NT 5.0
Plug And Play Architecture
CPL
Spooler
Setup
Plug and Play Manager
Enumeration HW event
control
manager
Enum
cntrl
Applications
HW
event
notify
User mode
Kernel mode
Exec
Plug and
Play Mgr
I/O
Plug
and Play
Power
Management
WDM Interface
Plug and Play bus drivers
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ACPI
PC Card
USB
WDM Device Drivers
PCI
WDM Device Tree
SCSI disk FDO
(disk.sys)
SCSI disk PDO
(scsiport.sys)
SCSI CD-ROM FDO
(cdrom.sys)
SCSI CD-ROM PDO
(scsiport.sys)
“Toaster” FDO
(toaster.sys)
SCSI adapter FDO
(scsiport.sys)
“Toaster” PDO
(pci_bus.sys)
SCSI adapter PDO
(pci_bus.sys)
PCI bus FDO
(pci_bus.sys)
PCI bus PDO
(Plug and Play
Manager)
Attachment (Functional Device Object, Physical Device Object)
Parent-child relationship
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Logical device instance
Windows Software Issues
• “State” on systems has grown out of control
– Poor separation of system, application, or user
state (history of one pc, one user, few apps)
– Applications put files in system directories
– Shared libraries shipped with applications
• versioning nightmare
– End user has no idea what each file does
• or what happens if it is deleted or replaced
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Solutions
• Guidelines to separate the state
• Better application guidelines
– ideally an app can be dropped onto the system
• Add an installation service to system
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takes a “package” and installs it
tracks versions of shared components
puts application files in separate directories
tracks ownership of files
Tools needed to create packages
Managing large Installations
Goals
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End user must not need to be administrator
Automatically install or update OS and apps
Keep SW consistent across the organization
Policies/apps assigned to groups of users
Support “roaming” users
Make system replacement possible
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Technology to make this happen
• Coda-like file system features
– client-side caching
– single instance store
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Directory service includes “Class Store”
Automatic application installation
Remote booting
Policy based management
Improved UI and tools
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File/Document Management
Client side caching
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Master copy of files live on the server
Copy is cached on the local system
Caching is done by network re-director
Data is stored in file system with
minimal meta-data
• Improves performance and availability
of network files and installed
applications
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Connected to a Network
1: Open any file - redirected to network
2: Store copy in client
side cache
3: Read from local
client side cache
4: Write-through cache
5: “Pin” cached files
to prevent eviction
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Working Off-line
1: Request to open
network file
2: Redirect to local
cached copy
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Reconnecting to the Network
1: Automatically copy
locally modified files
up to the server
2: Automatically copy
server modified
files to client
side cache
3: When file changes collide
Wizard walks user through
reconciliation process
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File/Document management
(cont)
• Server provides single instance store
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Asynchronous process on server
Detects duplicate files
Replaces with links to a master
Performs “copy-on-write”
• Drive letters, system files, other clutter
only available in “Advanced” explorer
views
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Directory Service
• Global, replicated, easily accessed place to
store things
• Class store resides in the directory
– Populated automatically by administration tools
– Takes a class ID and returns a path, or URL to
an application or component
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Centralized Management
• Administrator creates groups of users, e.g.
payroll, and assigns desktop properties and apps
to groups and/or individuals
• Profiles are stored in the directory
• Easy to create “locked down” systems
• End user performs no administration
– OS installs and upgrades automatically
– Application installation is automatic
– Users can log on anywhere and see the exact same
environment, including applications and documents
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Application Installation
• Applications appear on desktop, start menu,
and in class associations at log in
• Application installation is transparent no
matter how the App is invoked
• Application invocation patterned on object
instantiation for legacy apps
– Verify if App is installed and if the version is correct
– If version is incorrect, silent setup is performed
– App is invoked after verification
• System decides via policy if app should
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be installed normally, Cached to local disk, or Run from the net
App Deployment Model
Assigned & Published Applications
• Assigned Applications are automatically installed
– User can’t delete app from machine
• Published Applications are optional
– Installed via “Add/Remove Programs”
– Document invocation will auto-install too!
e.g.: click on Visio doc in email
• Apps deployed to users or machines
– App pushed to machine; pulled by user
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Deployment Process
Office 98 CD
Network Server
1: Create a network install for app.
2: Customize installation options
3: Assign application in policy
4: User in OU “receives” policy
5: At User Logon, the machine
receives portions of the app.
6: Upon user invocation, the app
is installed on user’s machine
Pat
08/12/97
“Sales Force”
Group Policy
Remote Boot
• Goals
– Enable Remote Boot of Windows NT
– Simplify management of server images
• Most costly problem with remote boot today
– Maintain ability to function offline
– Automatic OS update & simple repair
• Solution
– Remote boot solution based on caching and single
instance storage
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Remote Boot (cont’d)
• NT maps client physical storage to “D:\”
• “C:\” is a cache -- replica lives on net
– Entire contents of C:\ drive is placed on net
• i.e.: Each client has their own disk image
– Single instance storage (NTFS filter driver) eliminates
storage of duplicate files
• Enable flexible configuration without drive bloat.
E.g.: older app, different driver
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Remote Boot
• Client boots via new boot ROMs
• DHCP server hosts extensions
– Dialect between OS-less client & server
– Fully defined in NetPC specification
• Policy used to define client behavior
• DS accounts used for state storage
• Applet (OSChooser) sent as “bootstrap” code to
offer initial choices
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Scenario: New Machine
Machine
Machine
Account
Account
Install
Server
Remote Boot
Server
Directory
Services
Policy
Class
Store
Client A
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Client B
Scenario: Existing Machine
Machine
Account
Install
Server
Remote Boot
Server
Directory
Services
Policy
Class
Store
?
Client A
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Client B
Scenario: Machine Failure
Machine A
Account
Install
Server
Remote Boot
Server
Directory
Services
Machine
MachineBB
Account
Account
Policy
User Selects
“Replace Machine”
Client A
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Client B
Summary
• Plug and play is non-trivial
– requires significant hardware and software
• Application installation problems
– Architectural improvements,
– engineering discipline
• Large systems
– use caching and single instance store to
eliminate end user administration
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Questions?
?
08/12/97