dyer@arktouros.mit.edu (Steve Dyer) (08/29/90)
One of our users is trying to run a large Clipper database
application under DOS Merge under AIX PS/2 1.2, using
the UNIX file system as a DOS network drive. The Clipper
application apparently runs using some form of internal
overlays, meaning (I presume) that the .EXE file contains
overlays within itself and the linker adds code to open
the EXE after it starts running.
One apparent consequence of this is that it is not possible
to run more than one copy of the application on the same PS/2
at a time. That is, if I start up two copies of DOS Merge
and attempt to run the EXE, the first DOS Merge successfully
runs the application, but the second DOS Merge returns at
the C: prompt with 'Access Denied' when the program is
invoked.
Exactly what the problem is is isn't very clear, but
it seems to be at the interstices between DOS/network
drives/UNIX protections and DOS Merge's emulation of
same. The developer of the Clipper application reports
that he can run multiple copies on a network provided
that the EXE is set to be 'read-only'. Well, setting
this attribute under both UNIX and DOS has no effect here.
Can anyone DOS network savvy and/or DOS Merge savvy
comment on a workaround?
---
Steve Dyer
dyer@ursa-major.spdcc.com aka ...!{harvard,linus,ima,m2c,rayssd}!spdcc!dyer
dyer@arktouros.mit.edu, dyer@hstbme.mit.edubrian@alpha.la.locus.com (Brian D. Horn) (08/29/90)
In article <1990Aug28.180409.22536@athena.mit.edu> dyer@arktouros.mit.edu (Steve Dyer) writes: >One apparent consequence of this is that it is not possible >to run more than one copy of the application on the same PS/2 >at a time. That is, if I start up two copies of DOS Merge ... >Exactly what the problem is is isn't very clear, but >it seems to be at the interstices between DOS/network >drives/UNIX protections and DOS Merge's emulation of >same. The developer of the Clipper application reports >that he can run multiple copies on a network provided >that the EXE is set to be 'read-only'. Well, setting >this attribute under both UNIX and DOS has no effect here. Forgive me if I am a bit fuzzy, but as I recall DOS tries to do a DOS file lock on "writable" images. With Unix providing the file system access to the EXE the concept of a "writable" image becomes a little vague and hence almost ANY write access will do. The DOS lock (I believe) becomes a Unix enforced lock and hence the second DOS session trying to access the EXE is denied access. There SHOULD be a way of marking the EXE as read-only (but I cannot recall exactly how) as suggested by the Clipper developer which would defeat the locking and let you run more than one copy. Perhaps Dana Myers can answer this question better. (I went looking for him, but "no joy".)
sassan@locus.com (Sassan Behzadi) (08/29/90)
In article <1990Aug28.180409.22536@athena.mit.edu> dyer@arktouros.mit.edu (Steve Dyer) writes: >One of our users is trying to run a large Clipper database >application under DOS Merge under AIX PS/2 1.2, using >the UNIX file system as a DOS network drive. ....... > >One apparent consequence of this is that it is not possible >to run more than one copy of the application on the same PS/2 >at a time. That is, if I start up two copies of DOS Merge >and attempt to run the EXE, the first DOS Merge successfully >runs the application, but the second DOS Merge returns at >the C: prompt with 'Access Denied' when the program is >invoked. > >Can anyone DOS network savvy and/or DOS Merge savvy >comment on a workaround? > What happens if you set your C: drive as a "local" (non-Network) drive? You can use the MERGE command to do this: C> merge set drive local C> merge set handle local now try running the application. You may have to do this in all your DOS sessions running the Clipper database. Setting your C: drive as a non-network drive may let you startup multiple Clipper applications but the application might not function as a multiuser database. It's worth a try though. This could also be a real permissions problem, can the same user startup multiple instances of the same application? +-------------------------------------------------------------------+ | Sassan Behzadi - sassan@locus.com | | Locus Computing Corporation. | +-------------------------------------------------------------------+