Verifying Replication by Using Propagation Tests

Propagation files are files of varying sizes that are dropped into a replica tree to verify that replication is working. Because Ultrasound also tracks the amount of time required for the propagation file to replicate to all replica members, propagation files are also useful for identifying inefficient topologies or other replication delays.

You set up a propagation test to schedule propagation files to be dropped into the replica tree. You have a number of options when setting up propagation tests, including the following:

• Scheduling an immediate one-time test or a recurring test at the interval and time you choose.
• Choosing the size of the propagation file, ranging from 0 bytes to 1 MB.
• Specifying when the propagation test times out if replication does not complete, ranging from four hours to eight weeks.

Propagation files are located in a hidden directory under the replica root. The directory name is UltrasoundPropagationFiles.servername, where servername is the name of the server where the propagation file is dropped. The propagation file is named UltrasoundPropagationFile_GUID, where GUID is a unique identifier.

Ultrasound only tracks the replication of propagation files on servers that have providers installed on them. When a propagation test starts, a snapshot list of monitored replica members is created. This list defines the servers on which propagation files are tracked.