ASMCA is not detect the running ASM Instance in Oracle

Error
Our environment is in LINUX, We are trying to open ASMCA from GRID user but getting message like “ASM instance is not started” .
we have verified ORACLE_HOME it is set properly and ASM is up and running but still throwing error.

Cause
Missing entry of ASM home in /etc/oratab entry

Solution
Please make a entry in /etc/oratab by using text editor or VI editor

1. Check the ASM instance name in linux environment

$ ps -eaf | grep pmon
grid 9574 9374 0 10:13 pts/1 00:00:00 grep pmon
grid 29475 1 0 2019 ? 00:00:03 asm_pmon_+ASM


2. Open the /etc/oratab, vi editor next details
Note: last line is added which is in bold font. Grid home location:
GRID HOME: /u01/grid/11204/grid, ASM is running from grid home location.

$ vi /etc/oratab# Oracle entries
ORCLDB:/oracle/app/product/11.2.0.4:N
+ASM:/u01/grid/11204/grid:N