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Home -> Community -> Mailing Lists -> Oracle-L -> RE: looking for tool to help consolidate Oracle schemas within Or acle instances and Oracle instances on AIX servers
Can you clarify your assumptions in the statement that "there isn't much
difference in hardware requirements", particularly regarding RAM? Are
you assuming that the RAM allocated to the SGA's for each of the
instances on a machine can be tuned such that it is roughly equivalent
to the total RAM needed for a single integrated instance... That tends
to be an unusual in my experience-- two instances on a machine generally
require significantly more RAM than one instance would because of the
redundant dictionary caches, background processes, etc. In the
pathological cases (i.e. 20 instances on a single machine), that
redundancy got pretty hefty... =20
In addition, you don't see the same degree of benefit to differently timed workloads-- one instance may do its heavy batch processing from 1-5am, where another does its processing from 4-7am. If they were integrated, the second could take advantage of the SGA that the other wasn't using from 5-7 (or 1-4). If they are separate instances, though, you need both SGA's around all the time.
Justin Cave
Distributed Database Consulting, Inc.
http://www.ddbcinc.com/askDDBC
-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of DENNIS WILLIAMS
Sent: Wednesday, April 21, 2004 8:16 AM
To: 'oracle-l_at_freelists.org'
Subject: RE: looking for tool to help consolidate Oracle schemas within
Or acle instances and Oracle instances on AIX servers
Jaco=20
Here is what I believe.
1. Overall there isn't much difference in hardware requirements whether
all workload goes through a single instance or multiple instances. I
don't think you will be able to detect a difference. If you have other
test results, please post them.
2. Once you've got an application installed, don't move it unless you
have a good reason. If it ain't broke, don't fix it. Yes, I did change
my philosophy, but I have only applied that changed philosophy to new
applications. I didn't go back and consolidate existing applications.
3. Managers are tending to look at the database to DBA ratio. This is
ridiculous, of course, but their responsibility is ensuring their DBA
resources are being well-utilized. Until we propose something better,
they will tend to look at this ratio. Just because your managers aren't
looking at this ratio today doesn't mean they won't look at it tomorrow.
It would be ironic that you go through an extensive consolidation effort
only to have management decide they have too many DBAs now that the
ratio looks better.
4. I don't think there is a lot of difference between supporting X users
on one instance or across several instances. As you have outlined
yourself, there are factors both ways that tend to cancel each other
out. By consolidating instances you must examine resource usage more
carefully.
5. I think that DBA effort is minimized by configuring an instance
properly when it is installed and then leaving it alone. Too many DBAs
have the "perfectionism" disease. A lot of problems are self-inflicted.
6. If making continual changes promotes your value to management and
keeps you employed, then I am in favor of continual changes, since I
like a regular paycheck. But I'm still hoping for that independently
wealthy thing.
Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com=20
-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of J.Polet_at_Robeco.nl
Sent: Wednesday, April 21, 2004 5:52 AM
To: oracle-l_at_freelists.org
Subject: RE: looking for tool to help consolidate Oracle schemas within
Or acle instances and Oracle instances on AIX servers
Dennis,
It is very interesting to hear that you are tending to go the opposite direction based on your experience.
The benefits we are hoping the achieve is easier database management and
less hardware resources.
We know that management will become complexer when consolidating
schemas in instances but we think we can handle that by using the right
tools in the right way.
In our envirmont we do have same vendor applications with specific
Oracle requirements but most of our application are just looking for a
set of tables to store their data without extra requirements about the
oracle version or oracle features. Even some vendor applications, as a
result of their database indepency, are using the database for basic
datastore.
That is the reason why we think that we can consolidate most of our
applications in a minimum number of instances.
We are in fact already doing that in some instances for applications
for which there are no special requirements and for which there are no
risks of conflicts between application schema's as a result of for
example usage of public synonyms or user definitions.
Our idea is to set up a consolidated database environment consisting of
a minimum number of instances running two oracle versions. When an
application schema meets our requirements it can be added to this
enviroment. If it doesn't meet our requirements it will end up in a
dedicated instances and in some cases even on a dedicated UNIX server.
The costs for database management in the consolidated environment will
be the lowest.
This idea can only work when their is a management commitment on all
levels, Could that be the reason why this didn't work in your situation?
In order to create a stable consolidated database environment we need tools voor monitoring en managing resource usage.
Jaco
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(Embedded image moved to NL Telephone: +31 (0) 10 224 2045=20 file: pic05705.gif) E-mail:J.Polet_at_robeco.nl=20
Corporate ICT/BS DBA
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DENNIS WILLIAMS <DWILLIAMS_at_LIFETOU To:"'oracle-l_at_freelists.org'" <oracle-l_at_freelists.org>
CH.COM> cc: Sent by: Subject: RE: looking for tool to help consolidate Oracle schemas within Or acle =20 oracle-l-bounce_at_fr instances and Oracle instances on AIX servers =20 eelists.org
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20-04-2004 15:58 Please respond to oracle-l
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Jaco
What are the benefits you hope to achieve by consolidating schemas within an instance? I can see several potential problems, especially if these are vendor-supported applications. It may be difficult to upgrade to new Oracle versions because different vendors will provide support for a new Oracle version at different times. Another issue is that each schema may support a different group of users, and one group of users may be eager to move to a new Oracle version while another group of users doesn't see this as a priority. After years of trying to consolidate schemas as much as possible, I've tended to go the opposite direction in recent years.
Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com
-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of J.Polet_at_Robeco.nl
Sent: Tuesday, April 20, 2004 3:21 AM
To: oracle-l_at_freelists.org
Subject: looking for tool to help consolidate Oracle schemas within
Oracle instances and Oracle instances on AIX servers
Hi all,
I am currently working on a consolidation project. Within this project we want to consolidate Oracle schemas within Oracle 8.1.7.4/ 10g instances and Oracle instances on AIX 5.2 servers.
We see 3 potential problems:
1. How do we prevent instances and schema's influencing each others
performance?
2. How do we determine which schemas can be consolidated within the same
instance from a resource usage point of view?
3. How do we determine which instances can be consolidated on the same
server from a resource usage point of view?
To address our first problem we are looking at the Oracle Resource Manager for controlling the resource usage of schemas within the same instance and AIX Workload Manager to control resource usage of instances on the same server.
For our second and third problem we want to create a shortlist of 3 (combination of) tools to evaluate which should be able to: - Measure the usage of instance resources like buffer cache, redo/undo blocks, open cursors etc. on a schema level. - Measure the available instance resources within an instance - Measure the usage of server resources (CPU, Memory, Disk IO, Network IO) on a schema level and on an instance level. - Measure the available server resources within a server
Does anyone has an idea of which (combination of) tools I should put on this shortlist?
Thanks... Jaco
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