Specifying the preferred storage unit (UNIT) parameter

 

The system finds a place for a database file on auxiliary storage. The UNIT parameter specifies where to store the file.

Effective for Version 3 Release 6 the UNIT parameter is a no-operation (NOP) function for the following commands:

• Create Physical File (CRTPF)

• Create Logical File (CRTLF)

• Create Source Physical File (CRTSRCPF)

• Change physical File (CHGPF)

• Change Logical File (CHGLF)

• Change Source Physical File (CHGSRCPF)

The parameter can still be coded; its presence does not cause an error. It will be ignored. The UNIT parameter specifies:

• The location of data records in physical files.

• The access path for both physical files and logical files.

The data is placed on different units if:

• There is not enough space on the unit.

• The unit is not valid for your system.

An informational message indicating that the file was not placed on the requested unit is sent when file members are added. (A message is not sent when the file member is extended.)

 

UNIT parameter tips

In general, you should not specify the UNIT parameter. Let the system place the file on the disk unit of its choosing. This is usually better for performance, and relieves you of the task of managing auxiliary storage. If you specify a unit number and also an auxiliary storage pool, the unit number is ignored.

 

Parent topic:

Specifying database file and member attributes

 

Related concepts

Independent disk pools examples