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Sybase to UDB Migration - Code Freeze

P: n/a
Company is planning a Sybase to UDB migration that is projected to take
1 year. During that long period of time any Code Freeze put into place
would impact our users (we normally release code changes once a month).
Any suggestions on how to manage a partial code freeze while under
going a major migration like this one?

Nov 12 '05 #1
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P: n/a
aw***@yahoo.com wrote:
Company is planning a Sybase to UDB migration that is projected to take
1 year. During that long period of time any Code Freeze put into place
would impact our users (we normally release code changes once a month).
Any suggestions on how to manage a partial code freeze while under
going a major migration like this one?

I presume that the monthly updates are not major?
My recommendation would be to migrate a snapshort of the app and do
function migration. Once that is done, I'd roll forward to the newest
snapshot and tune that.
Once this is done (let's assume you are now, say 4 months behind) you
freeze, rollforward, retest/tune and cut over to DB2.
Perhaps you will need parallel production for one app delivery.

Just my two cents canadian.

Couple of thoughts for sanity checks:
* Do you have QA for the App to be migrated? How do you plan to prove
correctness of the migration?
Insufficient QA infrastructure is one of the top problems when
migrating, especially have a look at code coverage.
Listlessly clicking around on some forms while squinting the eyes is
not good enough. You need a testbed on Sybase and it needs to be
migrated to DB2.
* Keep in mind that your first cut (functional correctness) will be
emulating Sybase on DB2. It will be slow. That's OK!
You will then need to keep an open mind. Move from code tuned to
Sybase emulated on DB2 to code natively tuned to DB2 for the
performance critical areas.
* If your tooling provides Java UDF. Rip them out. Replace with UNFENCED
C (The MTK provides C source code)
* Check out my articles on developerWorks/DB2:
www.ibm.com search for "rielau".
I'm in process of updating the SQL Procedure Tracing, you will need it
as well as the profiler

have fun!
Serge
--
Serge Rielau
DB2 SQL Compiler Development
IBM Toronto Lab
Nov 12 '05 #2

P: n/a
aw***@yahoo.com wrote:
During that long period of time any Code Freeze put into place
would impact our users (we normally release code changes once a month).


I having been involved with several large app migrations in terms of the client OS, one technique used during the "code freeze" was to freeze the interface to the host system such that either the old
or new client OS could be used. This limited the types of changes possible for the application during the freeze, but did not prevent bug fixes from being produced.

A subset of that, to freeze a part of the database schema is also possible, but "once you have allowed some schema change..." need I say more? ;-)

--
Michael Lueck
Lueck Data Systems
http://www.lueckdatasystems.com/

Remove the upper case letters NOSPAM to contact me directly.
Nov 12 '05 #3

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