ABSTRACT
In addition to relational databases, Microsoft Azure provides several options for saving unstructured data, such as Table storage, BLOB storage, and virtual disks. Before we go into detail of these services, let us first study how to use local storage space on virtual machines running your service roles.
6.1 Local Storage When defining a cloud service role, you can allocate a local storage space for the role to use. A Local Storage is a special folder on the virtual machine that the role instance can use to save temporary data. Because the virtual machines hosting role instances are stateless, you are not supposed to persist with permanent data on a Local Storage. Although you can specify that data in the Local Storage should be preserved when the role instance is recycled, it is not guaranteed that the data will be permanently saved. For example, during role instance maintenance, Microsoft Azure may migrate your role instances to other virtual machines when there are errors on the hosting machines. Obviously, you will not be able to access the data on the original hosting machines in this case. If you want reliable data storages, you will need to use the database services we introduced in the previous chapter or use the data storage services that we will cover later in this chapter.
