The Question is:
Is there a way of removing sysgen parameters that have already been applied
before a reboot is performed?
If so how?
The Answer is :
There is no way to remove a system parameter -- the OpenVMS Wizard
will guess at the intended question.
If you wish to reset the value, the recommended approach is via
MODPARAMS.DAT and AUTOGEN or (less desirably) via SYSGEN or SYSMAN.
If the particular system parameter is a dynamic parameter, you can
use SYSGEN WRITE ACTIVE or the SYSMAN PARAMS WRITE ACTIVE command to
change the running value.
If you wish to reset the parameter value for the next reboot to a
new value, use MODPARAMS and AUTOGEN or use the SYSGEN WRITE CURRENT
or the SYSMAN PARAMS WRITE CURRENT command to store the value.
If you wish make a change to one or more values transient and thus
use the original value when the system next reboots, you can use the
SYSBOOT (conversational bootstrap) and set the WRITESYSPARAMS value
to 0 after all other SET commands and immediately before issuing the
CONTINUE command to continue the bootstrap.
If, on the other hand, you seek a way to roll back to older system
parameter values after an AUTOGEN pass, then you may well have a copy
of the old system parameters file in SYS$SYSTEM:. You can also load
and store the current parameters using the USE and WRITE commands in
the SYSGEN utility or in the SYSMAN PARAMS mechanism.
If you wish to use the conversational bootstrap mechanism (SYSBOOT)
to make temporary changes to system parameters, you can use the SET
command on the parameter(s) as required, and then issue the SYSBOOT
command SET WRITESYSPARAMS 0 just before the CONTINUE command to
continue the system bootstrap. This sequence will load the new
parameter value(s) into the active parameters, but will not update
the saved parameter value(s). You can then reboot the system to
reset the parameter values back to the original configuration.