[Linux-HA] 3 SERVERS in CLUSTER (db2)

Alan Robertson alanr at unix.sh
Tue Oct 4 05:41:04 MDT 2005


Laurent LE PRIEUR wrote:
> 
> ----- Original Message ----- From: "Alan Robertson" <alanr at unix.sh>
> To: "General Linux-HA mailing list" <linux-ha at lists.linux-ha.org>
> Sent: Tuesday, October 04, 2005 3:12 AM
> Subject: Re: [Linux-HA] 3 SERVERS in CLUSTER (db2)
> 
> 
> Le-Prieur Laurent wrote:
> 
>>
>> ---- Messages d´origine ----
>> De: Alan Robertson <alanr at unix.sh>
>> Date: Lundi, Octobre 3, 2005 9:10 pm
>> Objet: Re: [Linux-HA] 3 SERVERS in CLUSTER
>>
>>
>>> Laurent LE PRIEUR wrote:
>>>
>>>> Hello,
>>>>
>>>> I have activate the CRM for 3 nodes in cluster.
>>>>
>>>> I would wish to set up the following design
>>>>
>>>> 2 Nodes ACTIVE and 1 node PASSIVE connected on SAN Network.
>>>>
>>>> Each of the 2 active nodes launches DB2.
>>>>
>>>> With the structure and support IBM DB2, the directory for DB2 is
>>>
>>>
>>> /opt/IBM/db2>
>>>
>>>> If the versions of DB2 are not the same ones I am constrained to
>>>
>>>
>>> authorize the fail over on the passive node only for the first node 
>>> which would fall defective.
>>>
>>>> Can I put this operation places from there with the CRM and so
>>>
>>>
>>> yes how?
>>>
>>>
>>> I assume you have two different DB2 instances on the two active 
>>> machines?
>>
>>
>>
>> Yes Alan, two diffrent DB2 instances and potentially two different 
>> release (fixpack) for DB2 (one node active node with fixpak 8 and 
>> other with fixpak 10).
> 
> 
> Is this going to work?  Can you actually have two copies of db2 on the
> same machine at the same time?
> 
>> I have two partition per node on SAN :
>>
>> first partition mounted /opt/IBM/db2 (content /opt/IBM/db2, /var/db2 
>> (symbolic link)  and homedir for dasusr1)
>>
>> second partition mounted /datainst1 (content homedir for db2inst1 et 
>> db2fenc1 and the data for instance and databases).
>>
>> I have sync on all node /etc/passwd
>> /etc/shadow
>> /etc/group
>> /etc/services
>>
>> And i have disable in /etc/inittab this line for HA environnement
>> fmc:2345:respawn:/opt/IBM/db2/V8.1/bin/db2fmcd #DB2 Fault Monitor
>> Coordinator
>>
>> I will use the passive node if one (and only one) of active is fault 
>> or maintenance.
> 
> 
>> I think each machine needs to have its own homedir installed - 
>> somewhere in the homedir there hides the name of the machine it's 
>> installed on.
> 
> 
>> You need to have ONLY the tables move from one machine to another - 
>> not the homedir.
> 
> 
> Ok Alan, but is not the response of my initial question...
> 
> I would wish to set up the following design
> 2 Nodes ACTIVE and 1 node PASSIVE
> I am constrained to authorize the fail over on the passive node only for 
> the first
> node which would fall defective.

OK.

I misunderstood.  But, you will need to fail over the copy of the db2 
software as well as the tables themselves.

But the homedir (for recent copies of db2) also contains the name of the 
host it's running on.  So, it would be easier if you didn't fail over 
the homedir but installed the database twice, and failed over the tables 
instead of the whole homedir.

Otherwise, when it sees the wrong machine name when it starts up, it 
will not be happy and not do anything good for you.  But, if you fail 
over the tables, they don't have the host name in them.

And, yes, you can make it so that only one of these two will fail over 
to the third node - if you use version 2, and you define a CRM cluster.

I seem to have lost the pointer to the white paper on configuring DB2 
for HA.


-- 
     Alan Robertson <alanr at unix.sh>

"Openness is the foundation and preservative of friendship...  Let me 
claim from you at all times your undisguised opinions." - William 
Wilberforce



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