A read-only replicated folder is a replicated folder on a particular member in which users cannot add or change files. This is convenient for read-only folders that you want to keep up-to-date with a central server (or servers). For example, software installation folders, or folders that contain published reports or documents. Read-only replicated folders are also used by read-only domain controllers (RODCs) to keep the SYSVOL shared folder updated while preventing local changes.
Read-only replicated folders can be updated only with content from a read-write member of the replication group. All other attempts to write to the folder will fail. This includes performing an authoritative restore operation using a backup program.
When you make a replicated folder read-only, DFS Replication overwrites any content on the read-only member that has not yet replicated back to a read-write member. For this reason, it is a good idea to backup the folder, create a diagnostic report of replication and check the replication backlog before you make a replicated folder that contains existing content read-only.
Making a replicated folder read-only or writeable
|To make a replicated folder read-only or writeable by using the Windows interface|
Open DFS Management and then select the appropriate replication group in the console tree.
To use read-only replicated folders, the schema must include the Windows Server 2008 or newer schema additions. To view or manage replication groups that contain read-only replicated folders or members that are failover clusters, you must use the version of DFS Management that is included with Windows Server 2008 R2.
On the Memberships tab, right-click the appropriate replicated folder and member and then click Make read-only, or Make read-write.
|To make a replicated folder read-only or writeable by using a command line|
Open a command prompt window and then type the following command (to make a read-only folder writeable again, replace
Dfsradmin membership set /RGName:<replication_group> /RFName:<replicated_folder> /MemName:<DOMAIN\Server>/RO:true
Read-only replicated folders can impact the performance of a file server when an existing folder is set to read-only, or if the replicated folder is stored on the same volume as the Windows operating system.
- Changing the read-only or read-write status for a replicated folder causes DFS Replication to perform an initial replication and rebuild the DFS Replication database for the folder. On replicated folders that contain a large number of files, this can slow replication and consume system resources until the operation is complete.
- Storing a read-only replicated folder on the same volume as the Windows installation will result in decreased performance for that volume. The performance decrease occurs primarily when loading the first mini-filter driver. If there are other mini-filter drivers installed, such as an antivirus program or backup program, the additional performance decrease of using a read-only replicated folder is small.
The DFS Replication mini-filter driver intercepts all create and open (IRP_MJ_CREATE) operations for the volume on which the read-only replicated folder is located, and then inspects the destination to see if it is located in a read-only replicated folder. If the destination is in a read-only replicated folder, the driver fails the request to ensure that the folder remains read-only. Inspecting each create and open operation on a volume can impact performance if the read-only replicated folder is located on the system volume or any other volume for which there are frequent create or open requests to many different files.