If you’re using a multi-way rule and the same file changes on multiple sides of the synchronization before one of the copies can be synchronized you have what is called a multiple update. There are three ways that SureSync can deal with this situation. The default option is to log a warning letting you know the file changed in both places. With this option you will see the "Action suppressed. File changed or added to multiple paths since last successful synchronization" warning message. This allows you to look at the files, determine which you want to keep, or merge the changes together into one file. You can then manually copy the file you want to keep to the other paths.
A second option can be found on the "General" tab of the Rule. If you check "resolve multiple updates by copying the latest version" SureSync will resolve the conflict automatically by copying the file with the newest modified time and date stamp. This file in effect "wins" and replaces the other changed copies. This may or may not be something you want to turn on depending on the type of data in question.
It’s hard to predict how often multiple updates will happen in a particular environment. Some installations hardly ever see the situation surface while others see it more frequently. In environments where this error occurs frequently it is strongly recommended to implement File Locking.
When a user opens a file with this file locking active, SureSync will lock the file on all other paths involved in the Monitor. If another user accesses the same file, they will get a read-only copy. Once the other user has closed the file, SureSync will synchronize the file to the other machines and then release the lock. At that point, another user can access the updated copy with write access. This effectively eliminates most multiple updates.
The one instance where a multiple update can still occur with File Locking is when a connection loss occurs. If one or more of the paths in the monitor is offline, lock notifications cannot be sent to the path which can allow an update to occur. It is possible for multiple updates to occur if you stop the Monitor for a period of time as well. In those instances, it is recommended to use the "Resolve multiple updates by copying the latest" option to resolve the conflict. File Locking requires additional licensing. File locking is only available with Real-Time Monitors.