Accessing SAS Files through an Operating Environment

The following figure illustrates two client sessions that are accessing SAS files without using a SAS/SHARE server.

In this instance, your operating environment provides two types of access: read-only and read-write. With read-only access, multiple users can simultaneously read the same member or different members in the same library.

SAS files that have read-write access are usually associated with only one user. Some operating environments support only read access to libraries that are accessed directly by more than one user. Other operating environments permit two users to write to different files in the same SAS library but do not permit them to write to the same file simultaneously. Still other operating environments permit multiple users to write to the same file at the same time, even though doing so is not safe and often results in lost changes made by one or more users.

The only safe way for more than one user to share a SAS file (and on some operating environments an entire library) is to use a common third-party process to sequentially access the low-level parts of the file and coordinate updates to the data. SAS/SHARE is a product that regulates access to SAS files. For more information about the SAS library model, see SAS Language Reference: Concepts.