Re: V7: VMS or UNIX ?
Date: 1996/07/20
Message-ID: <31F091A7.6BA8_at_inmind.com>#1/1
It seems that someone took a rabbit trail on the different syntax
between UNIX and OPENVMS. I will 'attempt' to give you some reasons
for one or the other. (And throw my $.02 worth in on the 'openness' of VMS)
I have used a number of different OS's including VMS (VAX, ALHPA and OPEN),
NT, many flavors of UNIX including DYNIX (Sequent box), SCO Unix, Digital
Unix (including Ultrix, and OSF/1=DEC-UNIX) SCO Unix, UNIXWARE and LINUX and
HP UX. The question really has to do with: What are the system availability
requirments for the application 8x5? 24x7? I have not EVER seen a unix
box that had a 24x7 i/o intensive database application that could stay up
and running more than 30 days at a time. Conversely, I have seen MANY VAX
and ALPHA's running (Open)VMS that been up for 200+ days. and a few that
have been up for 1100+ days. Just in case you need help, that means that they
have not been rebooted in 3+years Most are not rebooted except a) when a
device fails and needs to be replace, or b) when they take a serious
power hit.
Configuring a CLUSTER is much easier than trying to figure out how to mirror the db on multiple systems. It is getting there, but the one thing the current UNIX boxes cannot guarantee READ consistency across multiple systems. VMS + CLUSTER can!
My overall reason for picking VMS over UNIX is stability & reliability (when the system crashes (if it ever does...) you usually don't have to pray that the filesystem didn't get corrupted causing you days of work to restore.)
Now, on the comment ( Open (HA!) VMS). Open VMS is one of only 3 OS's that has achieved the Xopen XPG4 rating. If you code to the POSIX standard, the code cna be very easily ported to other platforms. However, in my book, the only truly OPEN platform is DOS and the PC. You CANNOT just copy your code from one unix to another and have it work, most times, you can't even re-compile without making changes. And you call that OPEN? BTW if you are running on a VMS system with POSIX installed, you can use unix-like syntax to do whatever. (and if you are real desperate, you can edit your LOGIN.COM file (ie. .login) and add symbols for ALL your unix commands:
ls-la (note no space) :== DIR/DATE/SIZE
ls :== DIR
cd :== "SET DEFAULT "
type :== type/page !this is equal to type|more
hope this is useful...
Graham Miller wrote:
>
> hi,
> Relative directories in VMS (and OpenVMS) are:
>
> set def [.<Next Level Down>]
> .
.
.
bunch of stuff ommited...
.
.
.
>
> >*does* have a VMS equivalent...
> >(note the full stop after the first square bracket).
> >"set def" stands for SET DEFAULT. The general idea is a subtle
> >difference from the Unix way of thinking. In Unix "cd" means "change
> >directory" or "move me from where I am now into another direcory". In
> >VMS "set def" means "set default" or "tell the O/S where to look for
> >files if I don't stick a path on the front.
> >It's a subtle distinction and the only real "difference" is that if
> >you SET DEF to a non-existent directory, you will only get an error
> >message if you try to access a file in that directory.
> >Well, I hope that this is clearer than it looks to me! :-)
> >Pete
> >--
> >Peter Moore.
> >DBA, IS Ops,
> >Sequent Computer Systems Ltd, Weybridge, UK.
-- ============================== * Michael E. Austin * * austin_at_inmind.com * ==============================Received on Sat Jul 20 1996 - 00:00:00 CEST