Re: single node RAC system?

From: DA Morgan <damorgan_at_psoug.org>
Date: Thu, 31 May 2007 15:52:21 -0700
Message-ID: <1180651939.634986@bubbleator.drizzle.com>

herta wrote:

> On May 29, 5:39 pm, DA Morgan <damor..._at_psoug.org> wrote:
>> herta wrote:
>>> On May 26, 2:25 am, DA Morgan <damor..._at_psoug.org> wrote:
>>>> herta wrote:

>>>>> We are currently setting up our disaster recovery site (DRS).
>>>>> For Oracle, we want to use Dataguard to copy our databases to physical
>>>>> standby databases on a single system at the DRS.
>>>>> The single system is quite capable of running the Dataguard load, but
>>>>> should we need to run production at the DSR, it will not suffice. We
>>>>> would therefore like to set up this system as single node cluster, so
>>>>> that we can easily add instances if necessary.
>>>>> I tried installing clusterware on a single node, but the start of ONS
>>>>> fails with:
>>>>> Start of `ora.l27.ons` on member `l27` failed.
>>>>> CRS-1006: No more members to consider
>>>>> CRS-0215: Could not start resource 'ora.l27.ons'.
>>>>> Metalink article 2411114.1 suggests that the set up is possible,
>>>>> though the environment described there differs from ours (we use
>>>>> 64-bit SLES 10, Oracle RAC 10.2.0.3, ASM).
>>>>> It also warns that "this configuration is not certified or supported
>>>>> by Oracle Support Services".
>>>>> Has anyone tried setting up a single node cluster? If so, did you get
>>>>> the ONS error? How did you work around it?
>>>>> As to the support status, in theory, we could set up a two node
>>>>> cluster, and then take one node down. How would that differ from a
>>>>> single node cluster configuration?
>>>>> Alternative suggestions to achieve our goals are also welcome, of
>>>>> course.
>>>>> FWIIW, I opened an SR with Oracle four days ago, but they have yet to
>>>>> respond with something other than "we're looking into it'. A previous
>>>>> posting in ORACLE_DBA_EXPERTS also remained unanswered.
>>>>> I'm sort of pressed for time as the goal is to ship this to the DRS in
>>>>> three
>>>>> weeks time, and just getting a first copy of the physical databases on
>>>>> the storage is going to take a while.
>>>>> Kind regards,
>>>>> Herta

>>>> Build a two-node cluster and then shut down one machine.
>>>> Suggestions that you use VMWare will result in an unsupported environment.
>>>> --
>>>> Daniel A. Morgan
>>>> University of Washington
>>>> damor..._at_x.washington.edu
>>>> (replace x with u to respond)
>>>> Puget Sound Oracle Users Groupwww.psoug.org
>>> Thanks, Daniel.    We're considering this, using a test system as our
>>> second member, but we're wondering what impact this would have when
>>> we'd need to upgrade the software.  (We cannot ship the test system to
>>> the DR site.)  Has anyone actually done this?
>>> Kind regards,
>>> Herta
>> We just got done doing this for a public company where they are
>> doing Data Guard from RAC cluster to single instance but want the
>> ability to quickly turn that single instance into a cluster by
>> adding nodes.
>> --
>> Daniel A. Morgan
>> University of Washington
>> damor..._at_x.washington.edu
>> (replace x with u to respond)
>> Puget Sound Oracle Users Groupwww.psoug.org
> 
> Yes, I know I can set up a 2-node cluster, and then remove one node.
> I took the Oracle RAC course, and removing a system from the cluster
> and adding another one  was the last exercise of the training.
> 
> I'm just worried about how we can upgrade that one node.
> As explained, we want to run Dataguard standby databases on this
> system, and as you may know, Dataguard requires the primary and
> standby databases to run the same software versions.  I would hate not
> being able to install a critical patch in production just because it
> cannot be installed on our DR system.
> 
> Oracle has documented setting up a single node cluster in Oracle 9i
> without having to start from a two node cluster.
> My colleague read some Oracle 10g beta documentation with a similar
> setup, but the official documentation does not mention it anymore.
> I tried in vain to install a single node cluster, and the 'CRS-1006:
> No more members to consider' error has me worried that even when I'd
> start with a two node cluster and remove one node, the one node won't
> be upgradeable because it lacks other cluster members.
> 
> Given the changes between 9i and 10g, I am reluctant to follow that
> path without confirmation from Oracle that they will support this
> configuration.
> (Still no word from them after 10 days, though. :-(  )
> 
> Kind regards,
> 
> Herta

I'm a bit confused by what is confusing you.

A two-node RAC cluster is a special case. A cluster, to allow for rolling upgrades, should be three or more nodes.

-- 
Daniel A. Morgan
University of Washington
damorgan_at_x.washington.edu
(replace x with u to respond)
Puget Sound Oracle Users Group
www.psoug.org

Received on Thu May 31 2007 - 17:52:21 CDT