Re: Policy managed databases?

From: Martin Bach <>
Date: Tue, 26 Jan 2010 16:43:36 +0000
Message-ID: <>

Hi Mark,

I was looking into the same problems as you, I am very intrigued by the concept of server pools and policy based databases even though the largest cluster I have is only 3 nodes (but very powerful ones), so it's possibly not at all relevant for me.

BTW the only other useful source of information besides the Oracle doc I found is this one (the link might have unneeded line breaks in it): "Oracle Clusterware 11g Release 2 - a first glimpse under the hood"

I'd also check the online documentation and Metalink only-the downloadable library zipfile is woefully out of date and doesn't seem to get any updates (why not?).

IMO the whole concept of GNS, policy managed databases and server pools is geared towards users with a large number of cluster nodes (>4 definitely, more like 8-10) where you subdivide the n nodes into disjoint server pools.

There are 2 default pools-free (unassigned nodes) and generic (for "administrator-managed" databases). You can create your own of course, even nested! Administrator-managed database refers to the RAC database we know and have got to learn, policy-based databases are different, see below.

AFAIK there is a 1:1 mapping for (policy managed) databases and server pools. Each additional server pool has a name, minimum and maximum number of nodes and an importance. Clusterware can move nodes from the free pool (or maybe even from different pools whose importance is low and where there are more nodes than the minimum number of required nodes) to fill up the numbers.

There are also changes to services. For policy managed databases you can only chose between uniform or singleton services, i.e. services running on one node or all. More granularity is only available through administrator managed databases. It should be noted that the documentation states that Oracle adds undo tablespace and online redo log thread to policy managed databases if needed.

In addition to these things you can also define users (administrators) in Clusterware to further separate duties. Access Control Lists govern access to Clusterware resources (such as VIPs, ASM and db instances) and server pools. I reckon there are more than 1 or 2 hidden bugs, and the role separated management is turned off by default (thank god).

Now after all this theory I'll go off and implement this for real :)

When you just upgraded from CRS 10.2 -> 11.2 and haven't upgraded the 10g RDBMS (yet) you won't be able to make use of many of these features. All cluster nodes are "pinned" which is a prerequisite for running < 11.2 RDBMS instances. Not all cluster nodes need to be pinned, you could for example use nodes 1-3 for your 10.2/11.1 RDBMS and nodes 4-10 for 11.2. Search for "crsctl pin css" for more information about this...

I'll also present about this at the RAC & HA SIG in TVP (Reading) on Feb 10th :)



Martin Bach
OCM 10g

On 01/11/2010 10:27 PM, Bobak, Mark wrote:

> Has anyone seen any good papers on policy managed databases, server
> pools, etc?
> Iím setting up this new 11gR2 RAC. All new databases from the ground up,
> so, Iím trying out some of these new cluster management features.
> Iíve got my clusterware installed, implemented GNS, and thatís all
> looking good.
> Hereís where I get confused:
> I installed one policy-managed database, pointed it to a new server pool
> I defined, which I associated with all 4 of my nodes. That worked fine,
> no problems at all.
> Now, when I tried creating a second database, also policy-managed, that
> used the same server pool, it didnít allow me to do that. So, I tried
> creating a new server pool, but it said that there are no free servers
> in the cluster that can be assigned to the new server pool. So, then I
> tried re-creating the second database as admin managed, at which point
> it told me that if I wanted to start this database, it would take down
> the other database (the policy managed one). So, I canít share nodes at all?
> Iím getting the idea that a server can only belong to one server pool,
> and that only one database can be allocated to a server pool?
> What Iím trying to accomplish here is something similar to what I had in
> 10R2 and 11gR1. I want a 4 node RAC, 2 databases (online and mfg) and
> each node running two instances (one online and one mfg) with load
> balancing and failover setup across all four nodes. Optionally, enough
> control at the level of defining/modifying services, to be able to
> stop/start a particular instance running on a particular node. Pretty
> basic setup, really.
> Iím getting the idea that either Iím completely missing the concept of
> server pools and policies, or that they donít lend themselves well to
> the concept I outlined above.
> Does anyone have documentation (other than Oracle docs, which seem to be
> woefully inadequate in this area) or white papers related to server
> pools, policy-managed databases, etc?
> Should I not even bother?
> Usually I have a legacy application, and I just maintain status quo and
> move on, but, being that this application is all new from the ground up,
> I thought Iíd give all this new stuff a tryÖ.
> And of course, even if there was time and money for the OU class on this
> stuff, itís not even out yet!
> AdvThanksance,
> -Mark
Received on Tue Jan 26 2010 - 10:43:36 CST

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