Обсуждение: BUG #3748: Postmaster Service

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BUG #3748: Postmaster Service

От
"Sudarshan V Tantry"
Дата:
The following bug has been logged online:

Bug reference:      3748
Logged by:          Sudarshan V Tantry
Email address:      sudarshan.tantry@tcs.com
PostgreSQL version: 7.8.2
Operating system:   Redhat Linux
Description:        Postmaster Service
Details:

We are supporting a messaging system in which there are  two application
servers with cluster services.Cluster service does the job of shifting the
Application and Database services from one server to another if one of the
Application servers goes down.

Now,the problem is when we were testing the automatic shift over of
services,by manually stopping cluster service on one server using the
command "service clumanager stop" the Application and Database services get
shifted to another server,but Application services would be down due to the
fact that it cannot connect to the Database services since the postmaster
service is down.We check the status of Postmaster service with the command
"pg_ctl status".Even if we start the Postmaster service manually it goes
down whenever we stop the cluster service to shift the services back to the
first server.
Also postmaster services do not start even when the server is restarted.
We checked the postgresql.log in which we could find this: Unable to connect
to database
      Cannot find /var/lib/pgsql/DBDATA/data/postmaster.pid

DBDATA is the database service that is mounted on the application
server.That is getting mounted but postmaster would be found stopped.

Please let me a solution for this problem and also tell me why this problem
occurs.

Re: BUG #3748: Postmaster Service

От
Andrew Sullivan
Дата:
A couple things:

On Thu, Nov 15, 2007 at 12:49:40PM +0000, Sudarshan V Tantry wrote:
> PostgreSQL version: 7.8.2

There is no PostgreSQL version numbered that.

> We are supporting a messaging system in which there are  two application
> servers with cluster services.Cluster service does the job of shifting the
> Application and Database services from one server to another if one of the
> Application servers goes down.

So you have two application servers and two database servers?  Two servers
with the application and database on each?  I don't really understand.
Also,

> services,by manually stopping cluster service on one server using the
> command "service clumanager stop" the Application and Database services get
> shifted to another server,but Application services would be down due to the
> fact that it cannot connect to the Database services since the postmaster
> service is down.We check the status of Postmaster service with the command

In what sense do they get shifted to another server, if the postmaster
doesn't start up?

> Also postmaster services do not start even when the server is restarted.

Is there a start up script for postgres?

>
> DBDATA is the database service that is mounted on the application
> server.

I don't understand this sentence either.  But. . .

> That is getting mounted but postmaster would be found stopped.

. . .mounting a directory does not entail starting a database server.  These
are separate problems.  You have to have the PostgreSQL data area mounted,
and _then_ start PostgreSQL.  Perhaps your cluster thingy isn't doing it in
the right order.

In any case,

> Please let me a solution for this problem and also tell me why this problem
> occurs.

this doesn't seem to be a bug with PostgreSQL at all.  If anything, it has
something to do with this cluster thing you're using.  That's in general a
dangerous thing to do, and requires plenty of care.  See the high
availability parts of the manual to read general discussions of this, but
if you're having specific problems, I think you need to talk to the people
who make the cluster software.

A

--
Andrew Sullivan
Old sigs will return after re-constitution of blue smoke