The ASMSNMP user is an Oracle ASM user with privileges to monitor Oracle ASM instances. You are prompted to provide a password for this user during installation.

In addition to the OSASM group, whose members are granted the SYSASM system privilege to administer Oracle ASM, Oracle recommends that you create a less privileged user, ASMSNMP, and grant that user SYSDBA privileges to monitor the Oracle ASM instance. Oracle Enterprise Manager uses the ASMSNMP user to monitor Oracle ASM status.

During installation, you are prompted to provide a password for the ASMSNMP user. You can create an operating system authenticated user, or you can create an Oracle Database user called asmsnmp. In either case, grant the user SYSDBA privileges.