Abstract: SaaS mode introduces the multi-tenant environment,which may cause following two concerns raised for database storage:isolation of tenant’s data and expandability of tenant’s data.With research of the data storage and access mode for multi-tenant environments,this paper pointed out the model of ‘shared schema for data storage and indepen-dent schema for data access on shared database’．This model separates the schema for data storage and access for SaaS application,which would resolve the problems of ‘isolation of tenant’s data’．Meantime,the paper pointed out another XML-based model for multi-tenant data expansion,which would resolve the problem of ‘expandability of tenant’s data’．Furthermore,the report described the detailed solutions for the two models,which are proven practical and flexible.

Key words: SaaS,Multi-tenant,Data layer,Data storage