Need help to develop Plan Migrating DB2 on z/OS to DB2 UDBv9.5 on AIX 5.3

Posted on 2011-02-27
Last Modified: 2012-05-11
Hello all,
I need help developing and documenting a usable data migration plan that describes the strategy, preparation, and specifications for migrating/converting from current DB2v9 on z/OS to DB2 UDB on AIX environment. I looking for document examples of a fully treated plan used by someone who had done this kind of project. My data is going from the mainframe to AIX, what are the challenges and gotchas, if any, I should be aware of? Any major difference between the DB2 object on the mainframe or AIX that may "trip" a AIX newbie? Are there some links to where I can find more resources for this ind of project?

Any and all response will br highly appreciated.

Question by:Okonita001
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Accepted Solution

Kdo earned 350 total points
ID: 34996858
Hi Okonita,

Good questions.  :)

Before embarking on this task, you should understand this this is a full conversion/migration, just as converting from Oracle to DB2 would be.  There are a lot of similarities between DB2 for Z/OS and UDB/LUW, but that's mostly in the SQL and client ends.  The database engine (server) is a completely different code base with different requirements and tools.

The first thing that you'll need is a plan to migrate the data.  (Tables and table spaces.)  The Z/OS backups are not compatible with the LUW tools so you won't be able to simply restore a database backup.  The data will have to be migrated from Z/OS.  Depending on a several factors, you may be able to "Federate" the systems (IBM's terminology for logically linking the database server) so that the Z/OS tables can be seen from the LUW server.  You can then directly query the Z/OS tables from the LUW server and populate the LUW tables.  The other choice is to export the Z/OS data in IXF format and import it into the LUW server.  Both approaches have their strengths.  If you have a lot of data, the IXF export is probably the better choice.

The plan should include sizing.  Make sure that there is enough storage and the AIX server and that it organized in a logical fashion.

The next step will be to migrate the objects.  (Stored procedures, views, triggers, etc.)  The triggers should require very few changes, if any.  Most views should also require few changes, with the biggest concern being references to schemas that don't exist in the new environment.  Anything that references the system tables will have to be modified as the system environment (tables, views, names, etc.) is different.  Stored procedures will be the most work to convert as there will probably be SQL differences that will affect them.  And, of course, any references to system objects in the stored procedures.

Z/OS uses an EBCDIC character set.  AIX, like most all other servers, uses ASCII.  Any code (views, stored procedures, and external applications) the rely on the EBCDIC coding, or reference characters by binary value (e.g. '0x12') will have to be converted.

IBM has migration tools and checklists.  I'll track some down.  In the meantime, this is a "short list" of things to keep in mind.

LVL 57

Assisted Solution

giltjr earned 150 total points
ID: 34997603
Another issue with the EBCDIC vs. ASCII is sort order.  If a field/column contains alphanumeric data the sort order will could be different.  In ASCII numbers are lower in value (that is 1 would come before A if sorting in ascending order) in EBCDIC numbers are higher in value (that is 1 would come AFTER A if sorting in ascending order).

If you have large tables on the z/OS side you need to make sure you plan according on the AIX side.  z/OS handles files much differently than AIX.  I am fairly sure you can get better I/O performance on z/OS in some cases when compaired to AIX for very large table spaces.

Author Closing Comment

ID: 35046040
Both discussion were very correct but not complete and missing examples or references as I would expect  for a question that depends on experience.
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Expert Comment

ID: 35046279
I actually looked around and there are no references or examples.  This type of migration is not done alot.  I would suggest that you talk to IBM about getting somebody to help you.

I know we tested with DB2 on a distributed platform (I can't remember if it was Windows or Linux) and performance was less than desirable.  The process normally takes 1 hour on z/OS and the "distributed" people originally stated that with the processing power they had the process should take less 30 minutes and in a worse case situation it make take equal to that.

After about 6 hours and the process was less than half way done the test was stopped.
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Expert Comment

ID: 35046288
Hi giltjr,

I was also surprised by the lack of examples.

You moved from a Z/OS system to LUW?  If your tests suggest that LUW was taking about 10 times longer, it wasn't DB2, per se.  There was a configuration issue, memory management, I/O paths, or some other peripheral element that was responsible for the degradation.

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Expert Comment

ID: 35046866
Not too many companies migrate DB2 from z/OS to distributed platforms.  If they are migrating off of z/OS, they typically will go to a "cheaper" DBMS, like MySQL or PostgreSQL, or to DBMS that are considered better in the distributed world like Oracle.

The biggest issue was I/O.

The distributed team severely underestimated the I/O capability of our mainframe and severely overestimated the I/O capabilities of their SAN.   They did not really understand the native multipath support that mainframe environment has has for decades and what the lack of such support would do on the distributed side.  

They also over estimated the "advantage" of having more RAM and more faster CPU's.  The mainframe at that time only has 10GB and they out 64GB on the distributed server.    We had 5 CPU's rated at about 900Mhz vs. their 8 rated close to 3.0 Ghz.

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Expert Comment

ID: 35046933

There's always something to learn, huh?

Sorry that your lesson was so expensive.


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