fault tolerance with FreeBSD for old DOS app

Ted Mittelstaedt tedm at toybox.placo.com
Fri Mar 28 22:05:55 PDT 2008

> -----Original Message-----
> From: owner-freebsd-questions at freebsd.org
> [mailto:owner-freebsd-questions at freebsd.org]On Behalf Of B. Bonev
> Sent: Friday, March 28, 2008 3:31 AM
> To: bseklecki at collaborativefusion.com
> Cc: freebsd-questions at freebsd.org
> Subject: Re: fault tolerance with FreeBSD for old DOS app
> ----- Original Message -----
> From: "Brian A. Seklecki" <bseklecki at collaborativefusion.com>
> To: "B. Bonev" <b_bonev at mail.orbitel.bg>
> Cc: <freebsd-questions at freebsd.org>
> Sent: Tuesday, March 25, 2008 12:12 AM
> Subject: Re: fault tolerance with FreeBSD for old DOS app
> >
> > On Mon, 2008-03-24 at 19:36 +0200, B. Bonev wrote:
> >> I want advice for old DOS app on Windows PC, that I need to make on 2
> >> PC-s
> >> fault tolerant. Any advice for working solution on FreeBSD?
> >
> > Yep...rewrite the database in SQL with a PHP front end.  Import the data
> > from the old system.  Use a Radware/F5 Load Balancer for the web and
> > Slony-I for the database replication.
> >
> > Welcome to 2008.
> It is a accounting program, and will be too much efford for
> nothing. And I'm
> not a programmer.
> I 'm thinking for something like heartbeat, or realtime
> replication server -
> 2 identical machines,
> and when one of them break, staff to continue their work, without too much
> trouble...

You really want to be careful about using FreeBSD+Samba here.

Dos/Lanmanager/Windows networking provides a very rich set of
network file locking
calls, something like 20 or so.  Not all directly map to the UNIX
filesystem.  There are also vendor-specific stuff like Btrieve
that UNIX has never heard of.

If this old DOS app uses temp lock files in the directory the
data files are located in, you probably will be fine.

But if it uses some of the esoteric DOS file locking calls you
may find that when you move the accounting database off whatever
Novell or Windows NT or IBM Lanmanger server that it is currently
on, that suddenly you will find users bitching because some of
them cannot get into the accounting program.  And when the nightly
update is run, you may find the accounts having wrong dollar amounts
in them.

If your DOS app runs fine in a DOS window on Windows XP your
smartest thing you can do is right now, before Microsoft forces
everyone to stop selling XP, run out and forklift-replace -all-
of the clients with new XP systems.  And make your CFO understand
that they better start saving their money up because in another
5 years or so, when those XP systems start dying off, that it will
be the end of being able to use the accounting program.

With these DOS apps the server is actually unimportant.  You can
easily find an old Mylex SCSI RAID-5 controller and a pile of
10,000 RPM ultra SCSI disks out there that will give you all
the redundancy you need - run Windows 2K Server or 2003 Server
on that and you will have a bulletproof server.  All of the
horsepower in the application is actually being done on the
clients, and it is very easy for a client that has a hardware
fault - like for example a failing network adapter card - to
write garbage into the accounting database ans scotch it for

Stuff like this is why people are abandoning those old DOS
accounting programs right and left.  Like the other poster
said, start shopping for a new MySQL-based with PHP front
end accounting package.


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