Creating the TFS

The TFS is automatically mounted if the kernel is started in minimum mode. In this environment, the TFS is the in-storage file system and it defaults to the root file system. If it is to be used in other situations, it is made available by mounting. Because the TFS is a temporary file system, all data that is stored in the file system is discarded after it is unmounted. If you mount another TFS, that file system has only dot (.) and dot-dot (..) and nothing else.

If you are using kernel services in full function mode, you might want to mount a temporary file system over /tmp. If you do, it can be used as a high-speed file system for temporary files. However, you cannot recover vi files if the system goes down because vi writes temporary files to TMPDIR (/tmp by default). To recover these files, use the exrecover command, which automatically runs from /etc/rc.

Restriction: You cannot mount a TFS using a DDname. If the TFS is unmounted, all data stored in a TFS is lost; when remounted, the file system has only dot(.) and dot-dot(..) entries.

ServerPac installation jobs define the following FILESYSTYPE definition in SYS1.PARMLIB(BPXPRMFS):

FILESYSTYPE TYPE(TFS) ENTRYPOINT(BPXTFS)

Edit SYS1.PARMLIB(BPXPRMFS), that is, add the mount statement to mount a file system at the /tmp mount point. For example, you can add the following mount statement under the FILESYSTYPE TYPE(TFS) definition:

MOUNT FILESYSTEM('/TMP')
MOUNTPOINT('/tmp')
TYPE(TFS)
PARM('-s 10')

(-s 10) allocates 10 MB of storage

The following example shows the mount command for a TFS. Typically this specification would be in BPXPRMxx.

FILESYSTYPE TYPE(TFS) ENTRYPOINT(BPXTFS)
MOUNT FILESYSTEM('/TMP') TYPE(TFS)
MOUNTPOINT('/tmp')
PARM(' -s 10')

Note:

FILESYSTEM must be a unique name for the file system. Using the path name of the mount point makes it easier to understand output produced by commands such as df.
PARM specifies how much virtual storage the TFS can use. It can also be used to specify other information as listed in Parameter key options for the mount statement and mount commands. If PARM is omitted or is not valid, the TFS defaults to 1 MB. If the mount request specifies a size in megabytes that is too large for the address space, the request fails with an EMVSERR (9D) error. Try the request again, using a smaller value.
MODE is either RDWR or READ.
To specify that the temporary files are to be written to a specified directory instead of TMPDIR, use the TMP_VI environment variable.