20411B-ENU-TrainerHandbook

•DFS Namespace (DFS-N). Allows administrators to group shared folders that are located on different PROHIBITED servers into one or more logically structured namespaces. Each namespace appears to users as a

single shared folder with a series of subfolders. The subfolders typically point to shared folders that are located on various servers in multiple geographical sites throughout the organization.

•DFS-R. A multimaster replication engine that synchronizes files between servers for local and WAN network connections. DFS Replication supports replication scheduling, bandwidth throttling, and uses remote differential compression (RDC) to update only the portions of files that have changed since the last replication. You can use DFS Replication in conjunction with DFS namespaces or as a standalone file replication mechanism.

•Namespace high availability is required, which ONLY is accomplished by replicating the namespace

to multiple namespace servers.

•You need to hide the name of the namespace servers from users. This also makes it easier to

replace a namespace server or migrate the namespace to a different server. Users will then access the \\domainname\namespace format as opposed to the \\servername\share format. .

provides additional benefits such as support for access-based enumeration, and it increases the number of folder targets from 5,000 to 50,000. With access-based enumeration, you can also hide folders that users do not have permission to view.

•The Active Directory® forest must be at Windows Server 2003 or higher forest functional level.

•The Active Directory domain must be at the Windows Server 2008 domain functional level.

•All namespace servers must be Windows Server 2008.

Standalone Namespace

•An organization has not implemented Active Directory Domain Services (AD DS). USE

•An organization does not meet the requirements for a Windows Server 2008 mode, a domain-based namespace, and there are requirements for more than 5,000 DFS folders. Standalone DFS namespaces support up to 50,000 folders with targets.

•An organization is hosting a DFS namespace in a failover cluster. PROHIBITEDA standalone namespace is used when:

•DFS-R uses Remote Differential Compression USE

(RDC). RDC is a client-server protocol that

can be used to efficiently update files over a ONLY limited bandwidth network. RDC detects data

insertions, removals, and rearrangements in files, enabling DFS-R to replicate only the changed file blocks when files are updated.

RDC is only used for files that are 64 kilobytes (KB) or larger by default. DFS-R also supports cross-file

RDC, which allows DFS-R to use RDC, even when a file with the same name does not exist at the .

client. Cross-file RDC can determine files that are similar to the file that needs to be replicated, and it

uses blocks of similar files that are identical to the replicating file to minimize the amount of data thatSTUDENT needs to be replicated.

•DFS-R uses a hidden staging folder to stage a file before sending or receiving it. Staging folders act as caches for new and changed files to be replicated from sending members to receiving members. The sending member begins staging a file when it receives a request from the receiving member. The process involves reading the file from the replicated folder and building a compressed representation of the file in the staging folder. After it has been constructed, the staged file is sent to the receiving member; if RDC is used, only a fraction of the staging file might be replicated. The receiving member downloads the data and builds the file in its staging folder. After the file download completes on

the receiving member, DFS-R decompresses the file and installs it into the replicated folder. Each replicated folder has its own staging folder, which by default is located under the local path of the replicated folder in the DfsrPrivate\Staging folder.

•DFS-R detects changes on the volume by monitoring the file system update sequence number (USN) USE journal and replicates changes only after the file is closed.

•DFS-R uses a version vector exchange protocol to determine which files need to be synchronized. The protocol sends less than 1 KB per file across the network to synchronize the metadata associated with changed files on the sending and receiving members.

•DFS-R uses a conflict resolution heuristic of “last writer wins” for files that are in conflict (that is, a file PROHIBITED that is updated at multiple servers simultaneously) and “earliest creator wins” for name conflicts. Files

and folders that lose the conflict resolution are moved to a folder known as the Conflict and Deleted folder. You can also configure the service to move deleted files to the Conflict and Deleted folder for retrieval, should the file or folder be deleted. Each replicated folder has its own hidden Conflict and Deleted folder, which is located under the local path of the replicated folder in the DfsrPrivate \ConflictandDeleted folder.

•DFS-R is self-healing and can automatically recover from USN journal wraps, USN journal loss, or DFS-R database loss.

•DFS-R uses a Windows Management Instrumentation (WMI) provider that provides interfaces to obtain configuration and monitoring information from the DFS-R service.synchronized between servers across well-

10-30 Optimizing File Services

Alternatively, you can use the following Windows PowerShell cmdlet to enable data deduplication (for the volume E:, in this case):

3.Optionally, configure data deduplication jobs for a volume. USE

By default, built-in jobs are created and scheduled when you enable data deduplication for a volume.

If required, you can manually configure these jobs, or create additional jobs to further manage how data deduplication functions.Enable-DedupVolume E:

Additional Reading: Data Deduplication Overview ONLY

.

Several key scenarios can benefit from DFS-N and

DFS-R. These scenarios include:

• Sharing files across branch offices.

• Data collection.

• Data distribution.

the files to be used for a number of specific purposes. Critical data can be replicated to a hub site by using DFS-R and then backed up at the hub site by using standard backup procedures. This increases the branch office data recoverability if a server fails, because files will be available in two separate locations and backed up. Additionally, companies can reduce branch office costs by eliminating backup hardware and onsite IT personnel expertise. Replicated data can also be used to make branch office file shares fault tolerant. If the branch office server fails, clients in the branch office can access the replicated data at the hub site.