Windows Server 2008

9/26/2008

Windows Server 2008

File Services

·  help manage storage

·  enable file replication

·  manage shared folders

·  ensure fast file searching

·  enable access for UNIX client computers

The Distributed File System (DFS)

What does DFS do?

·  DFS offers wide area network (WAN)-friendly replication

·  highly available access to geographically dispersed files

·  DFSReplication is a new replication engine

·  Improvements over the File Replication service (FRS). The benefits of using DFSReplication are described below

·  In WindowsServer®2008, DFS is implemented as a role service of the File Services role. The Distributed File System role service consists of two child role services:

1.  DFS Namespaces

2.  DFS Replication

DFSNamespaces

·  formerly known as Distributed File System

·  allows administrators to group shared folders located on different servers and present them to users as a virtual tree of folders known as a namespace.

·  provides numerous benefits, including increased availability of data, load sharing, and simplified data migration

DFSReplication

·  multimaster replication engine that supports replication scheduling and bandwidth throttling.

·  uses a new compression protocol called Remote Differential Compression (RDC), which can be used to efficiently update files over a limited-bandwidth network.

·  RDC detects insertions, removals, and re-arrangements of data in files, thereby enabling DFSReplication to replicate only the changes when files are updated.

·  reduce the amount of bandwidth required to replicate new files.

The following figure illustrates how DFSNamespaces and DFSReplication work together. The processes marked 1 and 2 are described in more detail following the figure.

As the figure shows, when a user attempts to access a folder in the namespace

1.  the client computer contacts a namespace server. The namespace server sends the client computer a referral that contains a list of servers that host the shared folders (called folder targets) associated with the folder. The client computer caches the referral and then contacts the first server in the referral

2.  typically a server in the client’s own site unless no same-site servers exist or the administrator configures target priority.

The highlighted folder in the figure shows that it is hosted by shared folders on two servers, one in New York and one in London, to provide users in those sites with fast, reliable access to files. The shared folders are kept synchronized by DFSReplication. The fact that multiple servers host the folder is transparent to users, who see only a single folder in the namespace. If one of the servers becomes unavailable, the client computer fails over to the remaining server.

DFSReplication requirements

Before DFSReplication can be deployed, administrators must configure servers and storage as follows:

·  The Active Directory schema must be updated to include the new DFSReplication objects.

·  Antivirus software must be compatible with DFSReplication; contact your antivirus software vendor to check for compatibility.

·  Servers in a replication group must be in the same forest. You cannot enable replication across servers in different forests.

·  Replicated folders must be stored on NTFS volumes.

·  On server clusters, replicated folders should be located in the local storage of a node because the Distributed File System Replication service is not cluster aware and the service will not fail over to another node.

·  In Windows Server2008, for newly created domains operating at the ActiveDirectory domain functional level of Windows Server2008, DFSReplication is used by default for SYSVOL replication.

·  If your domain controllers are upgraded from another operating system to Windows Server2008, you must install DFSReplication on all domain controllers in the domain, raise the domain functional level to Windows Server2008, and then follow a migration process to move from using FRS replication of SYSVOL to DFSReplication.

DFSNamespaces requirements

·  Only servers running Windows Server2008 can host domain-based namespaces in Windows Server2008 mode.

·  Must contain an NTFS volume to host the namespace.

·  Must be a member server or domain controller in the domain in which the namespace is configured. (This requirement applies to every namespace server that hosts a given domain-based namespace.)

·  Can use multiple namespace servers to increase the availability of the namespace

·  The namespace cannot be a clustered resource in a failover cluster. However, you can locate the namespace on a server that also functions as a node in a failover cluster if you configure the namespace to use only local resources on that server.

For Server Hosting Stand-Alone Namespaces

·  Only servers running Windows Server2008 support access-based enumeration for stand-alone or domain-based (Windows Server2008 mode) namespaces.

·  Must contain an NTFS volume to host the namespace.

·  Can be a member server or domain controller.

·  Can be hosted by a failover cluster to increase the availability of the namespace

Review DFS Namespaces Server Requirements

A namespace server is a domain controller or member server that hosts a namespace. The number of namespaces you can host on a server is determined by the operating system running on the namespace server.

The following servers can host multiple namespaces:

·  Windows Server2008 Enterprise

·  Windows Server2008 Datacenter

·  Windows Server2003R2, Enterprise Edition

·  Windows Server2003R2, Datacenter Edition

·  WindowsServer2003, Enterprise Edition

·  WindowsServer2003, Datacenter Edition

Servers running the following operating systems can host only a single namespace:

·  Windows Server2008 Standard

·  WindowsServer2003R2, Standard Edition

·  WindowsServer2003, Web Edition

·  WindowsServer2003, Standard Edition

·  Any version of Windows2000 Server

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