This Knowledgebase article provides information about applications running on the passive server that can interfere with Neverfail Heartbeat file protection.
Applications should not be run on the passive server, as this will interfere with Neverfail Heartbeat file protection. Of particular concern are applications and or services that attempt to modify files, which are part of the protected data set.
If a service or application attempts to modify files on the passive server, the following will be observed:
- 'ApplyFSException' or 'Access Denied on a file that was in use' - errors logged in the Neverfail Event Log. The event log can be viewed by logging into a Neverfail Heartbeat Management Client connected to your server pair.
- A Full System Check will fail to complete successfully because files cannot be synchronized [File System Status Failed - system out of sync].
- If the file continues to change on the active server, it will appear on the 'Pending Tasks' list on the Data\File Sync and Verify Tab.
A service or application attempting to modify files on the passive server as a result of an application running on the passive server.
If you do observe these events, check that no applications are running on the passive server. The most likely applications or services to cause these kinds of exceptions are those specified in the Start or Stop scripts because they will include files within the protected file set.
If a service or application does not exit or stop cleanly on the passive server, it may be necessary to:
- Shut down Neverfail Heartbeat - leave the protected application running on the active server.
- Restart the passive server.
- Restart Neverfail Heartbeat on the active server.
- Allow a Full System Check to complete successfully.
Queue Sizes Increase
The size of the update queue is displayed on the 'System Status Control' panel of the Neverfail Heartbeat Management Client. A side effect of this problem going unchecked for extended periods of time is an increase in the size of the passive server (Safe) queue. File updates received on the passive server cannot be applied to disk because the files are in use. As a consequence, the size of the queue grows. This can cause the system to stop replication eventually, if it exceeds the MaxDiskUsage (default is 1GB on v6.0 and earlier and 10 GB on v6.2 and later). Data integrity cannot be guaranteed in this situation and the application may fail to start if a failover occurred at this point.
Neverfail Group recommends that applications should not interact with the protected file set on the passive Server.