Technical data

Device Support on OpenVMS Systems
7.4 Changes to the IO$_DIAGNOSE Function
S2DGV$L_32DSCTMO
S2DGV$L_64DSCTMO
S2DGB$L_DISCPRIV
Although not documented at the time, the PAD counts, S2DGV$L_32PADCNT
and S2DGV$L_64PADCNT were included in this group.
The implementation inadvertently conditionalized on the port’s ability to handle
command queuing instead of S2DGB$V_TAGGED_REQ.
The code has now been changed to conditionalize on S2DGB$V_TAGGED_REQ.
The PAD counts are still included in this group.
The documentation also stated that ports that do not support tagged command
queuing always behave as if S2DGB$V_TAGGED_REQ is 0. This applies to the
tagged queuing behavior of the ports. S2DGB$V_TAGGED_REQ still controls
whether the parameters previously mentioned are ignored, even on ports that do
not support tagged command queuing.
The reason these values are ignored when tagged command queuing is in use is
that they can affect other commands to the logical unit until the IO$_DIAGNOSE
command completes. (The timeout values are used as defaults for all commands
to the logical unit for the duration of the command.)
The OpenVMS I/O User’s Reference Manual for Version 7.3 has been updated to
reflect these changes and corrections.
7.5 Changed Behavior of IO$_SKIPFILE Function
V7.2
The performance of the IO$_SKIPFILE function was significantly improved in
OpenVMS Version 7.1 for certain SCSI tape drives. The new IO$_SKIPFILE
implementation functions correctly with all built-in OpenVMS tape functions such
as INIT, MOUNT, BACKUP, and COPY when tapes are formatted according to
the ANSI Standard X3.27-1987. This is the default tape standard for OpenVMS.
Higher performance for the IO$_SKIPFILE function is requested with the
modifier (IO$M_ALLOWFAST). When the IO$M_ALLOWFAST modifier is used,
IO$_SKIPFILE stops at the end of data rather than at double filemarks. For
more information about the IO$M_ALLOWFAST modifier, refer to the OpenVMS
I/O User’s Reference Manual.
In OpenVMS Version 7.2, SKIPFILE support is implemented through
a standard DCL interface, making the old SYS$ETC:MKSET.TXT and
SYS$ETC:MKSET.EXE files obsolete. Refer to the OpenVMS I/O User’s
Reference Manual for details about using the DCL interface.
7.6 CRCTX Routines Enhanced (Alpha Only)
V7.1-2
The system routines that you can use to manage the Counted Resource Context
Block (CRCTX) data structure have been improved. The following routines now
set and check the status (CRCTX$V_ITEM_VALID) of the CRCTX data structure:
• IOC$DEALLOC_CRCTX
• IOC$ALLOC_CNT_RES
Device Support on OpenVMS Systems 7–3