You can enable instances to start automatically after each system restart. The steps necessary to accomplish this task differ by operating system.
On Windows operating systems, the database instance that is created during installation is set as auto-started by default.
On Linux, UNIX and Windows operating systems, an instance created by using db2icrt is set as a manual start.
db2greg -getinstrec instancename='<instance name>'
db2greg -updinstrec instancename='<instance name>'!startatboot=1
db2iauto -on <instance name>