POSIX file systems are stored in BS2000 in container files, which correspond to the partitions used to store file systems in UNIX systems. Container files are BS2000 PAM files which are located on a pubset. Container files must not be stored on private disks or on Net-Storage. Container files on Shared Public Volume Sets (SPVSs) can only be used at any given time by the POSIX of a BS2000 system. Container files and other BS2000 files may be located on the same pubset.
A container file is processed solely by the POSIX subsystem. Its content may not be modified using other access methods.
From the point of view of a POSIX file subsystem, a container file represents a file system that is administered by the ported UNIX system kernel.
POSIX administrators and BS2000 system administrators with root authorization can set up container files when installing new POSIX file systems with the POSIX installation program (see “Administer POSIX filesystems”). The size of the container file and thus of the POSIX file system is also determined during this process. Subsequent resizing is possible via fsexpand.
In order to limit the memory space for a user, a separate POSIX file system with the corresponding size can be created for this user. In this way, the present memory space in BS2000 is used more efficiently.
For the sake of performance, it is best not to have the container files of extensive, frequently used POSIX file systems on the same pubset as the container file of the root file system.