Hercules V4.00.0 - User Reference Guide

6.8.6 Common parameters for AWS, HET and Fake Tape virtual files

MAXSIZE=

This specifies the maximum number of bytes for the emulated file. The value is
either n bytes or nx where x specifies the multiplier K, M, G, or T (see ”

Table 10 ”
at the end of this section for details). Specifying zero for this parameter means
“unlimited” (there is no limit on the file size). MAXSIZE defaults to “0”.

MAXSIZEK=

This is the same as MAXSIZE=, but specified in Kilobytes.

MAXSIZEM=

This is the same as MAXSIZE=, but specified in Megabytes.

EOTMARGIN=

Specifies the number of bytes remaining (before reaching MAXSIZEx) at which
point the tape device will signal the presence of the “End-of-Tape” marker (re-
flector), thus allowing the program to switch to the next tape. The value is either
n bytes or nx where x specifies the multiplier K, M, G, or T (see “

Table 10 ” at the
end of this section for details).

READONLY=

Specifies whether the tape is mounted read-only (without a write ring or with the
cartridge protect switch set to "write protect"). A parameter of 1 means read-
only; a parameter of 0 means read-write. If READONLY=1, RO or NORING is
not specified; READONLY=0 is the default. Note that READONLY=0 does not
override the host system file permission settings for the underlying AWS or HET
file. If the AWS or HET file is marked read-only, the tape will be mounted read-
only despite specification of READONLY=0.

Specifies that the tape is mounted read-only (without a write ring or with the car-
tridge protect switch set to "write protect"). RO and NORING are equivalent to
READONLY=1.

NORING

This is the same as RO.

Specifies that the tape should be mounted read-write, if possible. RW and RING
are equivalent to READONLY=0. This is the default if READONLY=1, RO or NO-
RING is not specified. Note that RW and RING do not override the host system
file permission settings for the underlying AWS or HET file. If the AWS or HET
file is marked read-only, the tape will be mounted read-only despite specification
of RW or RING.

RING

This is the same as RW.

DEONIRQ=

Specifies whether a device end is presented if intervention is required during
tape motion. A parameter of 1 selects this option; a parameter of 0 turns it off.

NOAUTOMOUNT

Indicates that support for guest-initiated automatic tape volume mounting is to
always be disabled for this tape device. Automatic guest tape-mount support is
automatically globally enabled for all virtual (non-SCSI) tape devices by default
whenever an allowable automount directory is defined via the AUTOMOUNT
system parameter or the automount console command. The NOAUTOMOUNT
option allows you to specifically disable such support for a given device.

The automount feature enables software running in guest operating systems to
automatically mount, unmount and/or query for themselves the host "virtual tape
volume" filename mounted on a tape drive, via the use of special CCW opcodes
(0x4B Set Diagnose and 0xE4 Sense ID) without any intervention on the part of
the Hercules operator. An example of such a program for DOS/VSE called
TMOUNT is provided in the util subdirectory of the distributed source code.

This is a sticky option. When specified, automount support for the device re-
mains disabled until the option is specifically removed via a devinit command
without the option specified. This means if NOAUTOMOUNT is enabled for a
device while global automount functionality is currently disabled (because no
AUTOMOUNT statement was specified at Hercules startup), then automount
functionality remains disabled for the device even should global automount
functionality be later manually enabled via an automount con-sole command.

When the 0x4B Set Diagnose CCW is used to auto-mount a virtual tape volume
onto a given tape drive, an absolute (fully-qualified) pathname should normally
always be specified, but need not be if a path relative to the currently defined
"default allowable" automount directory is used instead.

The default allowable automount directory is always the first "allowable" directory
that was defined, or else the current directory if no allowable directories were
specifically defined. There is always a default allowable directory whenever any
allowable or unallowable automount directories are defined.

Fully-resolved, absolute-full-path filenames are defined as being those which, for
Windows, have a ':' (colon) in the second position or, for other host operating
systems (e.g. Linux), have a '/' (slash) in the first position. Pathes which start
with a '.' (period) are considered relative paths and will always be appended to
the currently defined default allowable automount directory, before being resol-
ved into fully-qualified paths by the host system (i.e. only fully-resolved absolute
pathnames are used in the performance of the actual automatic tape volume
mount).

For example, if more than one allowable automount directory is defined and the
volume wishing to be mounted happens to reside in the second one, then a fully-
qualified absolute pathname should of course be specified (or else one that is
relative to the default directory which happens to resolve to the desired file).

All attempts to automount host files in any defined "disallowable" directory (or
any subdirectory thereof [or otherwise not within any defined "allowable" direc-
tory or subdirectory]) will be rejected. An error message is always issued in such
cases, just as one is whenever a successful mount or unmount is performed.

A sample guest automount program called TMOUNT for the DOS/VSE operating
system is provided in the "util" subdirectory of the distributed source code.