CDB and WinDbg can create user-mode dump files in a variety of ways.
Creating a Dump File Automatically
When an application error occurs, Windows can respond in several different ways, depending on the postmortem debugging settings. If these settings instruct a debugging tool to create a dump file, a user-mode memory dump file will be created. For more information, see Enabling Postmortem Debugging.
Creating Dump Files While Debugging
When CDB or WinDbg is debugging a user-mode application, you can also the .dump (Create Dump File) command to create a dump file.
This command does not cause the target application to terminate. By selecting the proper command options, you can create a minidump file that contains exactly the amount of information you wish.
Shrinking an Existing Dump File
CDB and WinDbg can also be used to shrink a dump file. To do this, begin debugging an existing dump file, and then use the .dump command to create a dump file of smaller size.