Introduction to Dfs. Limits of Dfs 260 characters per file path 32 alternatives per volume 1 Dfs...
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Introduction to Dfs
Limits of Dfs
• 260 characters per file path
• 32 alternatives per volume
• 1 Dfs root per server
• Unlimited Dfs roots per domain
• Volumes limited by system resources
Overview of Dfs Roots
• The Dfs Service is auto-installed with the installation of Microsoft Windows 2000 Server.
• Two types of Dfs roots can be configured on Windows 2000 Server computers: stand-alone and domain.
Stand-Alone Dfs Roots
• Stand-alone Dfs information is stored in the local registry.
• A stand-alone Dfs root permits a single level of Dfs links.
• When the Distributed File System snap-in is used to connect to existing stand-alone Dfs roots, all servers known to the browse list are retrieved because there is no unique NetBIOS name registered by Dfs-enabled servers.
• Stand-alone Dfs roots can be located on all supported file systems, although locating resources on NTFS-formatted partitions is recommended.
• Stand-alone Dfs roots offer no replication or backup; the Dfs root represents a single point of failure.
Domain Dfs Roots
• Multiple servers hand out referrals for the Dfs namespace.
• A fault-tolerant Dfs root is stored in Active Directory services and is replicated to every participating Dfs root server. Changes to a Dfs tree are automatically synchronized with Active Directory services.
• Fault-tolerant roots must be located on NTFS version 5.0–formatted partitions.
• The list of domains and servers is populated by querying the global catalog for all fault-tolerant Dfs roots.
• Dfs replication topology uses the existing Active Directory replication topology.
Configuring a Stand-Alone Dfs Root
• Stand-alone Dfs stores the Dfs topology on a single computer and does not provide fault tolerance.
• A stand-alone Dfs root is physically located on the server that users initially connect to.
• To create a stand-alone Dfs root, use the Distributed File System snap-in to start the New Dfs Root wizard.
Creating a Stand-Alone Dfs Root
Configuring a Domain Dfs Root
• Domain Dfs writes the Dfs topology to the Active Directory store, which allows links to point to multiple identical shared folders for fault tolerance.
• Domain Dfs supports DNS, multiple levels of child volumes, and file replication.
• To create a domain Dfs root, use the Distributed File System snap-in to start the New Dfs Root wizard.
Configuring New Dfs Links
• Users can browse folders under a Dfs root without knowing where the referenced resources are physically located.
• After you create the Dfs root, you can create Dfs links.
• To create a Dfs link, use the Distributed File System snap-in to open the Create A New Dfs Link dialog box.
Creating a Dfs Link
• FRS is installed automatically on all Windows 2000 Server computers.
• FRS is configured to start automatically on all domain controllers and manually on all stand-alone and member servers.
• The Active Directory store uses FRS to synchronize the directory among all the domain controllers.
• Active Directory services automatically generates a ring topology for replication among domain controllers in the same domain.
• The ring structure ensures that there are at least two replication paths from one domain controller to another.
Site and Domain Structures
• A site is made up of one or more IP subnets that identify a group of well-connected computers.
• Domain structure and site structure are maintained separately in Active Directory services.
• A single domain can include multiple sites, and a single site can include multiple domains.
Single Domain with Single Site
Single Domain with Multiple Sites
Multiple Sites with Multiple Domains
• Intra-site replication occurs between domain controllers within a site.
• Replicated data is not compressed.
• The default replication interval is five minutes.
• Replication is trigger-based (notification and pull).
Inter-Site Replication• Inter-site replication occurs between domain controllers
in different sites.
• You can specify the time when inter-site replication should occur. The default replication interval is three hours.
• You can specify the network transport for use in inter-site replication.
• Inter-site replication is compressed, regardless of the transport used.
• Inter-site replication compression reduces the data on the network by 88 to 90 percent.
• Inter-site replication is not configured automatically; it must be configured by an administrator.
Knowledge Consistency Checker (KCC)
• The KCC generates a ring topology for replication among domain controllers in the same domain.
• The ring structure guarantees that there are at least two replication paths from one domain controller to another.
• The KCC analyzes the replication topology within a site to ensure that the replication topology is efficient.
Unique Sequence Numbers (USNs)
• When a directory object is updated at a domain controller, a USN is assigned.
• When the domain controller writes the change into the directory, it also writes the USN.
• Each domain controller maintains a table of the USNs that it receives from every other domain controller in the domain.
• USNs eliminate the need for precise time stamps for changes.
• USNs simplify recovery after a failure.
• Changes to the %systemroot%\SYSVOL folder on any domain controller are automatically replicated to other domain controllers within the site.
• The replication topology and process are separate but identical to Active Directory replication.
• Windows 2000 Server sets up a default folder structure for SYSVOL.
Replicating Dfs Fault-Tolerant Roots
• Dfs and file replication support a number of features.
• Each Dfs root or link can reference a replicated set of share consequences.
• Dfs replication is disabled by default; use the Distributed File System snap-in to enable replication.
Configuring FRS for Inter-Site Replication
• Use the Active Directory Sites And Services snap-in to configure inter-site replication.
• To configure the FRS settings, you must create a new site link for the inter-site transport protocol listed in the console tree.