Re: Database Upgrade/Migration Dilemma
- From: rjsearle@xxxxxxxxx
- To: RWeiss@xxxxxxxxx
- Date: Thu, 26 Oct 2006 16:49:41 +1000
Hi Rick,
I'm not a DBA God, not even close, but I have designed and managed some
v.big migration projects between platforms and technologies. I've got the
following thoughts for you.
1. Maybe you could use MVs over the link? This may help solve the
problem associated with the source DB changing while you copy it to the dest
DB. But you may still have some downtime for indexing etc (DBA Gods should
comment on this idea)
2. migrating without testing is just folly
3. Object to the decision, in writing, supported by your assessment of
the risks and a lower risk alternate strategy that meets their business
needs. This way they are forwarned
4. and finally, Get that resume ready
What level of service is required of this application(s)? Keeping the
app(s) up while the data is migrated adds risk and complexity (read: cost)
to the migration. Do they really *need* the application running while
migratimg or is this someones clever idea? Maybe it is mission critical
with downtime considered very costly. If that's the true need then so be
it, but the migration strategy needs to be aware of all these needs and
designed accordingly.
What is the organisations risk appetite? or, What is the business value of
the information in the DB? What is their risk appetite? Can the
organisation tolerate the higher risk of their approach in the interests of
saving a few bob?
I hope this helps
Russell
On 10/26/06, Rick Weiss <RWeiss@xxxxxxxxx> wrote:
I just had an interesting and disturbing discussion with damagement and
wanted to run this by the DBA Gods that read this list.
We are planning to migrate out production environment from Oracle 8i (
8.1.6) on AIX to Oracle 10g (10.2) on Linux. My current plant is to do
the data moves (about 150 tables) as CTAS via database links. (are there
better options? exp/imp won't go back that far) The biggest kicker came in
this afternoon - our Java head wants to do the migration with the
application up and accessible.
This just seems to me to be courting disaster. My suggestion was to take
everything down, back up the entire environment and then do the moves prior
to repointing the applications and bringing them up.
Another kicker is they don't want to test prior to pulling the trigger.
The worst thing is they made the decision while I was out of town @ OOW.
Should I get my resume' ready?
Thank you for any insights you may have.
Rick Weiss
Oracle Database Administrator
Student Assistance Foundation
P.O.Box 203101
2500 Broadway
Helena, MT 59620-3101
rweiss@xxxxxxxxx
(406) 495-7356
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