Probably my most popular blog post of all time – certainly the one most commented upon – was called Changing the Hostname for a DB2 Server.  If you work in a shop that uses the same image (i.e. a Windows backup, VMWare image, or some other form of snap-shotting a Windows computer) containing DB2 for LUW for multiple implementations you will have run into a problem.  When changing the “Computer name” or hostname, the DB2 instance fails to start with an SQL1042C error.

I won’t repeat the entire blog post here – that’s why I included the link above – but I do need to post an update on the location of the important db2nodes.cfg file.  The db2nodes.cfg file now (in DB2 version 9.7) resides in the instance directory.  On a default Windows DB2 installation, that would be x:\ProgramData\IBM\DB2\DB2COPY1\DB2

Please be sure to follow the rest of the instructions on the original post to clear the SQL1042C error.