i am monitoring disk using SNMP and its showing disk utilization 300% not sure what the issue
Is it Windows, Linux, AIX, Solaris, NAS, or SAN?
If this is node that uses net-snmp, such as Linux, there is a known issue with net-snmp in that the fields are limited to 32 bit which causes the values to be truncated. There is an old thread about this here:
Large drives reporting incorrectly