We are running an SSO environment with one master and three media
servers. In our initial configuration, HP told us to set the
ST_ATS_ENABLED to zero. Veritas is now telling us to set the value to
one.

The official HP definition of this parameter is:
If st_ats_enabled is set to 0 in the system config file then the driver 
will not attempt to reserve a tape device using the SCSI RESERVE
command.  
The default value of st_ats_enabled is 1, meaning the driver will
attempt 
to reserve the tape device.

I have two questions.

First - what should we set it to? Zero apparently gives control to
Netbackup.
One apparently gives control to the OS.

Second - if the answer is to set it to one, then can anyone verify that
it allworks as advertised, IE the OS does in fact cleanly do what it is
supposed to?

Thanks,

Jeff