We highly recommend having over 80GB of hard drive space on your main C: drive for Core iQ.
The data drive is the area of most concern for us when speaking of drive space, but the consequences of disk space being low on the C: drive can be equally detrimental. When processing large queries, with sizable data, the PostgreSQL database engine will page to disk. Although the database is installed on the separate partition, the active partition that the OS is installed on tends to be the DBMS’s first choice for paging. If there is not adequate free space on the active partition, large queries can fail and halt operation. In addition, any subsequent upgrades of the Postgres DB may fail, due to lower disk space.