SAS 9.4 Language Reference, 6th Edition

environments. See the SAS documentation for your operating environment for more

information.

Sequential Data Libraries

SAS provides a number of features and procedures for reading from and writing to files

that are stored on sequential format devices, either disk or tape. Before you store SAS

libraries in sequential format, you should consider the following:

• You cannot use random access methods with sequential SAS data sets.

• You can access only one of the SAS files in a sequential library, or only one of the

SAS files on a tape, at any point in a SAS job.

For example, you cannot read two or more SAS data sets in the same library or on

the same tape at the same time in a single DATA step. However, you can access:

• two or more SAS files in different sequential libraries, or on different tapes at the

same time, if there are enough tape drives available

• a SAS file during one DATA or PROC step, and then access another SAS file in

the same sequential library or on the same tape during a later DATA or PROC

step

Also, when you have more than one SAS data set on a tape or in a sequential library

in the same DATA or PROC step, one SAS data set file might be opened during the

compilation phase. The additional SAS data sets are opened during the execution

phase. For more information, see the “SET Statement” in SAS DATA Step

Statements: Reference.

• For some operating environments, you can read from or write to SAS data sets only

during a DATA or PROC step. However, you can always use the COPY procedure to

transfer all members of a SAS library to tape for storage and backup purposes.

• Considerations specific to your site can affect your use of tape. For example, it might

be necessary to manually mount a tape before the SAS libraries become available.

Consult your operations staff if you are not familiar with using tape storage at your

location.

For information about sequential engines, see Chapter 37, “SAS Engines,” on page

745.

Operating Environment Information

The details for storing and accessing SAS files in sequential format vary with the

operating environment. See the SAS documentation for your operating environment

for more information.

Tools for Managing Libraries

SAS Utilities

The SAS utilities that are available for SAS file management enable you to work with

more than one SAS file at a time, as long as the files belong to the same library. The

advantage of learning and using SAS Explorer, functions, options, and procedures is that

596 Chapter 26 • SAS Libraries