disk utilization

disk utilization

Hello I am running a version of Opmanager on my Network and it is monitoring about 12 servers.
one of my servers has an alert for 100% disk utilization, but when checked the real utilization is only about 79%.
i have checked the device assets to make sure the HD size is correct. I dont know what i need to do to make the opmanager read the correct used space...
if you need info please let me know.
ps. sorry if this is a double post but i cant see if my last post worked...

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