Scientific Computing Program

1

• Scientific Computing Program
• Distributed File Systems
• Dr.Nidal Kafri
• Presented by
• Abed Hamarsheh

2
Goals Of Presentation

• What is Distributed File System?
• Distributed file system requirements
• Microsoft Distributed File System (DFS).

3
Distributed File System

• What is Distributed File System?
• Distributed file systems support the sharing of
  information in the form of files throughout the
  intranet.
• A distributed file system enables programs to
  store and access remote files exactly as they do
  on local ones, allowing users to access files
  from any computer on the intranet.

4
DFS Requirements

• Hardware and operating system heterogeneity
• Scalablility
• Should have the capability to hold large amount
  of data of customers in transparent location in
  distributed environment.
• File Architecture and Organisation
• Globle File System
• Location transparent Access
• Consistency
• One-copy (updated)

5
DFS requirements(cont...)

• Security
• Single sign via User ID and Password.
• Encryption of transferring data.
• Availability
• Replication mutiple copies of a file are
  produced and are kept on distributed servers.
• Increase fault Tolerance in case a server crash
  client can access replicated file from other
  servers.
• Log based recovery/ restart

6
DFS requirements(cont...)

• Performance
• Line speed , Bandwidth (WAN)
• Minimize number of transmission and distance
  between client and server.
• Replication
• Caching Cache size and Management
• Read Caching and Write Caching
• Disk Caching vs Memory-Caching.

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Microsoft DFS

• Provides a logical namespace for access to files
  distributed across the network.
• Name transparency
• Fault Tolerance
• Load Balancing
• Location transparency
• Ease of Administration

8
Network Shares Today

• Users typically work with multiple shares on a
  daily basis
• Share names often have little to do with share
  functions
• Mapped drives are common
• P ? \\BZU1\Rpts
• H ? \\BZU2\Users
• Drive mappings are group and machine dependent
• (Ritaj) H ?\\BZU3\Public
• (Development) H ? \\BZU2\Users

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Logical Namespaces

• A logical namespace solves many of these problems
• Multiple machines can be mapped to single logical
  names
• Single drive mapping can accommodate the entire
  namespace
• Simplify and hide the physical topology
• Consistent, global naming for users

10
Logical Network NamespaceAn Example
birzeit.edu
Branches
Ritaj
Students
Centers
Faculties
Art
Science
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Distributed File System Building the Logical
Namespace

• Client and Server component
• Organizes network file shares
• Provides logical structure to physical storage
  resources
• Global, uniform, customized namespace
• Translates logical names to physical shares
• Protocol independent
• Non-Windows servers can be in the namespace (e.g.
  Netware via NCP, Unix via NFS)

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DFS FunctionsClient Server Architecture
DFS Client
DFS Client
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DFS FunctionsName cracking
( O\ mapped to DFS Root )

• Cooperation between DFS client and server.

Open O\Ritaj\ExamSCOM7341\1.XLS
\\BZU8\Public
DFS Link
Ritaj\
ExamSCOM7341\
1.XLS
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DFS FunctionsTopology Management

• Protocol Independent
• Uses CIFS to communicate between client and
  server
• Uses underlying file protocol to connect to
  remote share
• CIFS for Windows
• NCP for Netware Servers
• NFS for Unix Servers

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DFS FunctionsTopology Management

• Store logical to physical mapping in a reliable,
  globally accessible location

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DFS FunctionsTopology Management
\\Ritaj.Birzeit.edu

• Domain Based DFS
• Topology stored in Active Directory
• Can have multiple DFS Servers on DCs or any
  member servers
• Managed by MMC Snap-in
• Uses Domain Name to root the namespace

Active Directory
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DFS FunctionsHigh Availability
DFS Client
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DFS Internals

• Terminology
• DFS Root Provides DFS namespace information to
  clients. Also provides physical storage for
  portions of namespace.
• DFS Link Logical name of a folder that is
  redirected to some network share(s).
• DFS Replicas Network shares that are actually
  used by clients that access the DFS Link

19
Distributed File System
Client side
Explorer(or any application)
Win32 API (CreateFile(\\M1\Products\Office\setup
.exe))
User
Kernel
NTOSKRNL.EXE
MUP.SYS
DFS
\M1\Products \Office-gt M2\Office
nwrdr.sys
Etc.
rdr.sys (SMB)
20
Distributed File System
Client side
Explorer(or any application)
Win32 API (CreateFile(\\M1\Products\Pinball\setu
p.exe))
User
Kernel
NTOSKRNL.EXE
MUP.SYS
DFS
\M1\Products \Office-gt M2\Office
nwrdr.sys
Etc.
rdr.sys (SMB)
\Pinball-gt Games\Pin
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Windows 2000 Features

• Domain DFS support
• Fault tolerant Root Replicas
• Site Aware Referral Service

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Scenario
Intranet
InternetInformation Server
DFS
Firewall or proxy
Internet
Internal and external sites can browse corporate
information published in DFS. DFS eases
publishing, since under the covers, the DFS maps
a physical location to a logical namespace.
Transparent naming, load balancing, and data
availability are all leveraged
23
Software Distribution
Site B
Site A
As sites are added, clients are referred to
replica shares that are within the site. If
replica share does not exist in the clients
site, the client is referred to one of the shares
in some other site
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• T H A N K Y O U
• Abed Hamarsheh