Re: Checking if a RAC database has one or more node down

Select thread#, status from gv$thread;

On Fri, May 17, 2019 at 9:15 AM Mladen Gogala <gogala.mladen_at_gmail.com> wrote:

> Essentially, RAC cluster is a dynamic thing. Instance can join the
> cluster, leave the cluster or even be evicted. Granted, evictions are much
> less frequent these days than with the previous releases, but they still do
> happen. A RAC cluster is comprised of the instances which are currently in
> the cluster. When an instance leaves the cluster, there is no certainty
> that it will ever come back or the administrator may even use srvctl to
> remove the instance. When an instance joins the cluster, a reconfiguration
> will happen in order to distribute the lock resources between the nodes.
> Cluster only knows about the current instances comprising it. Not just
> that, if your CRS are deployed on more than 2 servers, it is entirely
> possible to have the servers sub-divided into server pools and have
> different databases running om separate server pools.
> On 5/17/19 8:52 AM, Ls Cheng wrote:
>
> Hi
>
> How do we know the desired count of instance?Just because someone says so
> or it can be obtained from somewhere? In your example
> of cluster_database_instances is 8 but gv$instance returns 4 how do you
> know 4 is the desired count?
>
> BR
>
>
>
>
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> On Fri, May 17, 2019 at 2:46 PM Luis Santos <lsantos_at_pobox.com> wrote:
>
>> Thanks for all replies!
>>
>> Let's dig into my need. When I said *just SQL* I mean that my need is to
>> know if a RAC node is down while connected, and just connected, to the
>> database. No matter the node. Of course I'm aware of srvctl ou crsctl
>> commands, but they are out of my need scope.
>>
>> And querying GV$INSTANCE alone will no work. If a node is down it will
>> be missing from GV$INSTANCE, but how much nodes is my goal?
>>
>> Digging again: I'm talking about a simple monitoring script. With no
>> human (*or AI robot*) DBA querying.
>>
>> Up to now I have been using, with relative sucess, the comparision of count(*)
>> from GV$INSTANCE to the value of cluster_database_instances database
>> parameter.
>>
>> But now we have a Exadata machine with 8 nodes, but with only 4 nodes
>> actives for a specific RAC database. The count(*) from its GV$INSTANCE é
>> 4 and the value from cluster_database_instances parameter is 8.
>>
>> So, my qustion again: is it possible to design a simple query, while
>> connected to RAC databases, to show if one (or more) node(s) from the,
>> let's say, desired count of instances, is missing?
>>
>>
>> *--*
>> *Att*
>>
>>
>> *Luis Santos *
>>
>>
>>
>> Em qui, 16 de mai de 2019 às 23:22, Suresh Rajagopal <sureshr7_at_gmail.com>
>> escreveu:
>>
>>> crsctl stat res -w "TYPE = ora.database.type"
>>>
>>>
>>> On Thursday, May 16, 2019, 2:45:29 PM PDT, Mark W. Farnham <mwf_at_rsiz.com>
>>> wrote:
>>>
>>>
>>> select inst_id,status from gv$instance;
>>>
>>>
>>>
>>> *From:* oracle-l-bounce_at_freelists.org [mailto:
>>> oracle-l-bounce_at_freelists.org] *On Behalf Of *Luis Santos
>>> *Sent:* Thursday, May 16, 2019 4:51 PM
>>> *To:* ORACLE-L
>>> *Subject:* Checking if a RAC database has one or more node down
>>>
>>>
>>>
>>> Is there a way, using just SQL when connected to a RAC Oracle database
>>> (whatever the version), to check if all nodes are up and runing?
>>>
>>>
>>>
>>> *--*
>>>
>>> *Att*
>>>
>>> *Luis Santos*
>>>
>>>
>
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> --
> Mladen Gogala
> Database Consultant
> Tel: (347) 321-1217
>
>

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