IMS to DB2-- Big Problems
Al Silio
Let me explain my predicament: The place where I work (the
name of which will remain anonymous) has used IMS as its
database system for a long time. Of course, it's an IBM
mainframe. Well, a couple of years ago, the powers that be
decided in their infinite wisdom that we needed a new
system and that the new system should use DB2-- relational
instead of hierarchical. Now, I have no problem with them
wanting a new system--- the old one was in disrepair due to
all the maintenance that was done on it. And I have no
complaint with switching to DB2-- the state of the art, the
wave of the future, much more powerful, etc. In fact, I was
looking forward to it with enthusiasm. But with hindsight
being 20/20, I wish we had left well-enough alone. The
implementation of the new system has been totally botched.
The reason is that it was decided that it was too expensive
to implement the entire system at once, so they opted for a
"phased implementation". In order to do this, they had to
find a way to allow the old IMS applications that will
continue to exist for the time being to run alongside the
new DB2 applications. The solution was to come up with
what's called a "bridge" to translate all IMS access into
DB2, with the IMS application being none the wiser (as far
as it's concerned, it's making IMS calls--the bridge
intercepts all database calls, retrieves the requested data
from DB2 tables, and returns the data in the format the IMS
program expects). It sounds ingenious, but it's
difficult to implement. I knew it was a bad idea when I
first heard about it, and told anybody who would listen it
was a bad idea, but my opinion carries no weight. Well, as
you might guess, we're having major problems with it now
that it's been implemented and the database has been
converted to DB2. Quite simply, it doesn't work. And on top
of that, we're having big-time performance problems with the
new DB2 applications. Needless to say, I'm very down on DB2
and long for the days of IMS when things were much simpler
and better. And just my luck, I've been made the "on-call"
person--- I'm the one who gets called in the middle of the
night when the jobs/programs don't work, which is often. Has
anyone had a similar experience with going from IMS to DB2?
What a nightmare! Well, I'm through bellyaching.
Dionysus
C. McNiel
Oddly enough my company decided on the same basic approach that yours
did. IMS needed to go and DB2 needed to stay. The cost of converting the
43 systems that used IMS to DB2 in one pass was too much so the 'Bridge'
concept was used. However, our company purchased a product from Mainware Inc.
called DL/2 which is an IMS <-> DB2 transparency product. My experience on
the conversion has been fairly good. The product seems to work very well for
what it is doing and the performance of the existing IMS applications has been
excellent. We have not put the system into production yet but, are looking
to do so before the first of the year. I assume that the solution that you
are using is 'home grown' if things are as bad as you say you may want to
talk to mainware about the solution they provide.
MAINWARE
612-932-9154
***
Standard Company Employee disclaimer
Sean Dunn
are just starting to look at DL/2 now. We hit their technical guys
with 100 or so questions on top of clarifications from the glossies,
and the responses have been reasonably good.
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*** Sean Dunn, Wolverhampton, England ***
*** E-mail: se...@lilydale.demon.co.uk ***