export ORACLE_SID=+ASMMount the diskgroup using the below command:
export ORACLE_HOME=<Your Grid Infrastructure Home>
sqlplus / as sysasm
select name,state from v$asm_diskgroup;
alter diskgroup DG_NSOQACC mount;
do you have all the disks available in that diskgroup DG_NSOQACC ?
SQL> alter diskgroup DG_NSOQACC mount; alter diskgroup DG_NSOQACC mount * ERROR at line 1: ORA-15032: not all alterations performed ORA-15040: diskgroup is incomplete ORA-15042: ASM disk "2" is missing from group number "1"
select disk_number, mount_status, header_status, mode_status, state, name, label, path from v$asm_disk where group_number=1 order by disk_number;