If you accidentlly applied ROLLFORWARD command to the standby HADR database, you can put the database back to the rollforward pending mode by using db2 supplied utility db2rfpen.
$ db2rfpen on hadb
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IBM – Reset ROLLFORWARD Pending State
The db2rfpen tool is a utility to switch on the database rollforward
pending state.
It will also reset the database role to STANDARD if the database is
identified using the database_alias option.
In a non-HADR environment, this tool should only be used under the
advisement of DB2 service.
In an HADR environment, this tool can be used to reset the database
role to STANDARD.
SYNTAX: db2rfpen on < database_alias | -path log_file_header_path >
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Primary Global LFH file = /db2home/db2ap/NODE0000/SQL00001/SQLOGCTL.GLFH.1
Secondary Global LFH file = /db2home/db2ap/NODE0000/SQL00001/SQLOGCTL.GLFH.2
Original rollforward pending state is Off.
Setting rollforward pending State to On.