Is this a SQL server by any chance? It's normal for SQL to "consume" all the available memory that has been allocated (unless configured by the DBA's).

From a guest OS perspective;

Standby = Memory that contains cached data and code that is not actively in use

Modified = Memory whose contents must be written to disk before it can be used for any other purpose

As an example, my vCenter MSSQL server with 32GB RAM allocated has 31.16GB consumed where 11.2GB is in use, 15.6GB standby and 5.7GB free (figures rounded).

This looks like normal MSSQL behavior to me.

Cheers,

Jon