IDS Forum

Re: Multiple DBs vs Multiple instances

Posted By:
Date:

Ok, I'll stick my oar in.

Aside from the previous posts - there is an additional advantage to multiple
production instances - if you have different types of processing occurring
on each instance - for example one may be a DSS instance and another an OLTP
instance. Allows you to tune each database/instance for it's given need.

cheers
j.
----- Original Message -----
From: "Richard Snoke " <dsnoke@us.ibm.com>
To: <ids@iiug.org>
Sent: Thursday, March 13, 2003 2:28 PM
Subject: Re: Multiple DBs vs Multiple instances [696]


>
>
>
>
> This is sometimes a difficult choice.
>
> Multiple databases in one instance: On the minus side: all the work on
> all the db's is done by the same set of virtual processors, and all that
> work uses a common set of shared memory segments. The thread scheduler in
> IDS is not terribly sophisticated, and lots of work against one database
> may slow down work against another database. On the plus side,
> adminsitration is consolidated: all the db's are in the dbspaces of one
> instance. This may be a negative. It depends on your attitude about
> administration. Lastly, all the databases in an instance share the same
> logical logs. That can affect recovery times since the log records are
> jumbled together.
>
> Multiple instances with just one database per instance: Easier to keep
> things separated, but you'll have all the processes of each instance
> running on the system. If the machine has enough CPU's, then this may be
> just fine. With few CPU's the processes of one instance may starve the
> processes of other instances.
>
> I urge customers to have three separate instances: one each for the
> production system, the training system, and for the DBA's to play. I urge
> them to have the production system on a physically separate box from the
> others, just so that errors in training or testing new versions or the
like
> doesn't affect the production system (since that one is what the whole
> exercise is really about.) The training and DBA systems can share a box
as
> long as everyone is willing to risk an occasional crash and whatever
> response time hiccups might occur.
>
> My personal preference is for multiple databases in one instance as long
as
> everyone is getting adquate response and throughput.
>
> Cheers,
> Dick Snoke
> Consulting IT Specialist (certified)
> IBM Data Management Solutions
> 404-487-1595
> dsnoke@us.ibm.com
>
>
>
> "Terrence Mu...."
> <terrence@wagerwo To: ids@iiug.org
> rks.com> cc:
> Sent by: Subject: Multiple DBs vs
Multiple instances [692]
> forum.subscriber@
> iiug.org
>
>
> 03/13/2003 12:57
> PM
>

>
>
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>
>
> What are the pros/cons of have multiple databases in one instance
> as opposed to having multiple instances with just one database.
>
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Messages In This Thread

• Multiple DBs vs Multiple instances
  Terrence Mullins -- Thursday, 13 March 2003, at 12:57 p.m.
  • Re: Multiple DBs vs Multiple instances
    Zev Berezin -- Thursday, 13 March 2003, at 2:03 p.m.
    • Antw: Re: Multiple DBs vs Multiple instances
      Andreas.KUTSCHE@spar.at -- Friday, 14 March 2003, at 3:14 a.m.
  • Re: Multiple DBs vs Multiple instances
    Richard Snoke -- Thursday, 13 March 2003, at 2:28 p.m.
    • Re: Multiple DBs vs Multiple instances
      Jack Parker -- Thursday, 13 March 2003, at 2:58 p.m.
      • Re: Multiple DBs vs Multiple instances
        John Bejarano -- Thursday, 13 March 2003, at 3:54 p.m.
  • Re: Multiple DBs vs Multiple instances
    Obnoxio The Clown -- Thursday, 13 March 2003, at 5:01 p.m.

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