Collaboration in the Enterprise from the perspective of Anthony Holmes, an IBM Accelerated Value Program Leader (Premium Support Program).

Working Collaboration Blog

Information about cluster.ncf

Anthony Holmes  21 January 2010 05:20:06 PM
Here is some information about the cluster.ncf file that is created for any server or client that makes a connection to a cluster.

Whenever a server that is a member of a cluster is accessed, Notes records information about all the servers in the cluster, so that it can try to fail over to other cluster members in the future if the original server is ever unavailable. Domino servers do the same thing when they contact other servers in clusters.

The information about all the servers in the cluster is (I believe) kept in RAM, but it also gets written to a file called cluster.ncf. It's documented that this is actually written to cluster.ncf when the Notes client is shut down.

The fact that the file contains a ".ncf" extension might lead you to suspect that is is a form of Notes database (like ".nsf", ".ntf", ".ndk"...). But if you try to open it in Notes, you can't. That's because cluster.ncf is a simple text file. You can open it in Notepad or any other text editor.

Here's a sample cluster.ncf file, showing information about a single cluster of servers:

Time=11/10/2007 03:15:21 PM (CA257371:001760C4)
HomeCluster
CN=Server1A/O=Org
CN=Server1B/O=Org


In this case the first line give information about the time the cluster information was picked up by the Notes client. On the left hand side it's in simple text: "Time=11/10/2007 03:15:21 PM".
The text value is imprecise and ambiguous: is it 10th November or 11th October? Would things break if someone switched their Regional Settings from US to almost anywhere else in the world? What time zone was in use when this time was recorded?

The information in brackets gives more precise information:
 (CA257371:001760C4)
This hex information isn't a DocumentID, replica ID or UNID. Instead it is time and date information. Translated it says "Time Zone: 10 Hours East of Greenwich, with DST, Year: 2007, Month: October, Day: 11th; Time Hour: 15 (with DST)/Time Hour: 14 (without DST), Minute: 15, Second: 21, Ticks (sixtieths) of a second: 00

Information about how to decode these numbers can be found here:

How to Interpret the Hexadecimal values in a Time/Date value
http://www-01.ibm.com/support/docview.wss?rs=899&uid=swg27003019



The second line of the cluster.ncf gives the name of the cluster: HomeCluster

The third and fourth lines give the names of all the cluster members in the cluster, whether or not the user has yet had the need to connect to them. If there were four servers in the cluster, then all four servers would be listed here. In this case the user has definitely connected to Server1A. They may or may not have ever connected to Server1B, but if Server1A is ever unavailable, the Notes client will know where to go.


If this person connected to other clusters, the cluster.ncf file would contain additional Time; Cluster Name; Cluster Member Name(s) appended to the file.



As always, many thanks to the customer who asked me about clustering and cluster.ncf. It gave me a good reason to have a look at the nuts and bolts of how this works.