Cloud computing provides a multitenant feature that enables an IT asset to host multiple tenants, improving its utilization rate. The feature provides economic benefits to both users and service providers since it reduces the management cost and thus lowers the subscription price. Many users are, however, reluctant to subscribe to cloud computing services due to security concerns. To advance deployment of cloud computing, techniques enabling secure multitenancy, especially resource isolation techniques, need to be advanced further. Difficulty lies in the fact that the techniques range and cross various technical domains, and it is difficult to get the big picture. To cope with that, this paper introduces technical layers and categories, with which it identifies and structures technical issues on enabling multitenancy by conducting a survey. Based on the survey result, this paper discusses technical maturity of multitenant cloud computing from the standpoint of security and the needs for developing both technical and operational security toward the development and wide deployment of multitenant cloud computing.