Re: [GENERAL] cluster question

[Alex Samad]

On 17 August 2017 at 10:51, Ian Barwick  wrote:

> On 08/16/2017 02:41 PM, Alex Samad wrote:
> (...)
> >
> > okay think I have it setup, but when i do a switch over it gets stuck
> here.
> >
> >
> >
> > NOTICE: STANDBY PROMOTE successful
> > NOTICE: Executing pg_rewind on old master server
> > NOTICE: 3 files copied to /var/lib/pgsql/9.6/data
> > NOTICE: restarting server using '/usr/pgsql-9.6/bin/pg_ctl  -w -D
> /var/lib/pgsql/9.6/data -m fast restart'
> > pg_ctl: PID file "/var/lib/pgsql/9.6/data/postmaster.pid" does not exist
> > Is server running?
> > starting server anyway
> > NOTICE: STANDBY FOLLOW successful
>
> From the repmgr README:
>
> >> You must ensure that following a server start using `pg_ctl`, log output
> >> is not send to STDERR (the default behaviour). If logging is not
> configured,
> >> we recommend setting `logging_collector=on` in `postgresql.conf` and
> >> providing an explicit `-l/--log` setting in `repmgr.conf`'s
> `pg_ctl_options`
> >> parameter.
>
> i.e. when the old primary is restarted with:
>
> /usr/pgsql-9.6/bin/pg_ctl  -w -D /var/lib/pgsql/9.6/data -m fast
> restart
>
> the calling process hangs, waiting for logging output from pg_ctl.
> In "repmgr.conf" set "pg_ctl_options" to something like:
>
> pg_ctl_options='-l /path/to/log'
>
>
> Regards


Thanks, simple when you know, too many new things to look at



>
>
> Ian Barwick
>
> --
>  Ian Barwick   http://www.2ndQuadrant.com/
>  PostgreSQL Development, 24x7 Support, Training & Services
>

Re: [GENERAL] cluster question

[Ian Barwick]

On 08/16/2017 02:41 PM, Alex Samad wrote:
(...)
>
> okay think I have it setup, but when i do a switch over it gets stuck here.
>
>
>
> NOTICE: STANDBY PROMOTE successful
> NOTICE: Executing pg_rewind on old master server
> NOTICE: 3 files copied to /var/lib/pgsql/9.6/data
> NOTICE: restarting server using '/usr/pgsql-9.6/bin/pg_ctl  -w -D 
/var/lib/pgsql/9.6/data -m fast restart'
> pg_ctl: PID file "/var/lib/pgsql/9.6/data/postmaster.pid" does not exist
> Is server running?
> starting server anyway
> NOTICE: STANDBY FOLLOW successful

From the repmgr README:

>> You must ensure that following a server start using `pg_ctl`, log output
>> is not send to STDERR (the default behaviour). If logging is not configured,
>> we recommend setting `logging_collector=on` in `postgresql.conf` and
>> providing an explicit `-l/--log` setting in `repmgr.conf`'s `pg_ctl_options`
>> parameter.

i.e. when the old primary is restarted with:

/usr/pgsql-9.6/bin/pg_ctl  -w -D /var/lib/pgsql/9.6/data -m fast restart

the calling process hangs, waiting for logging output from pg_ctl.
In "repmgr.conf" set "pg_ctl_options" to something like:

pg_ctl_options='-l /path/to/log'


Regards

Ian Barwick

--
 Ian Barwick   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services


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Re: [GENERAL] cluster question

[Alex Samad]

On 15 August 2017 at 16:35, Andreas Kretschmer 
wrote:

>
>
> Am 15.08.2017 um 05:15 schrieb Alex Samad:
>
>> Hi
>>
>> Quick question.  I have a 2 node cluster - each node has its own ip.
>>
>> But from reading this, I really need a 3rd ip, which potentially floats
>> between the nodes to which ever is the master / rw node.
>>
>> Is that right? Sort of makes sense I guess
>>
>>
> That's one way to solve that problem. If you are using repmgr/repmgrd you
> can call own commands on events like failover. And, if you are using
> pgbouncer or connection-pooling you can change the config for pgbouncer
> (redefine the databases and there connection strings) and reload pgbouncer.
> You can do that with the event-notification commands defined in your
> repmgr-config.
> Other solution: with some Java-drivers you can define several databases
> and checks (if the database read-only or rw), the next PostgreSQL 10 will
> offer a similar feature.
>
>
okay think I have it setup, but when i do a switch over it gets stuck here.



NOTICE: STANDBY PROMOTE successful
NOTICE: Executing pg_rewind on old master server
NOTICE: 3 files copied to /var/lib/pgsql/9.6/data
NOTICE: restarting server using '/usr/pgsql-9.6/bin/pg_ctl  -w -D
/var/lib/pgsql/9.6/data -m fast restart'
pg_ctl: PID file "/var/lib/pgsql/9.6/data/postmaster.pid" does not exist
Is server running?
starting server anyway
NOTICE: STANDBY FOLLOW successful


doesn't look like the output from https://github.com/
2ndQuadrant/repmgr/blob/master/README.md

NOTICE: STANDBY PROMOTE successful
NOTICE: Executing pg_rewind on old master server
NOTICE: 5 files copied to /var/lib/postgresql/9.5/data
NOTICE: restarting server using '/usr/local/bin/pg_ctl -w -D
/var/lib/postgresql/9.5/node_1/data -m fast restart'
pg_ctl: PID file "/var/lib/postgresql/9.5/node_1/data/postmaster.pid"
does not exist
Is server running?
starting server anyway
NOTICE: node 1 is replicating in state "streaming"
NOTICE: switchover was successful






> PS.: please don't top-posting.
>
>
>



> Regards, Andreas
>
> --
> 2ndQuadrant - The PostgreSQL Support Company.
> www.2ndQuadrant.com
>
>
>
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Re: [GENERAL] cluster question

[Andreas Kretschmer]

Am 15.08.2017 um 05:15 schrieb Alex Samad:

Hi

Quick question.  I have a 2 node cluster - each node has its own ip.

But from reading this, I really need a 3rd ip, which potentially 
floats between the nodes to which ever is the master / rw node.


Is that right? Sort of makes sense I guess



That's one way to solve that problem. If you are using repmgr/repmgrd 
you can call own commands on events like failover. And, if you are using 
pgbouncer or connection-pooling you can change the config for pgbouncer 
(redefine the databases and there connection strings) and reload 
pgbouncer. You can do that with the event-notification commands defined 
in your repmgr-config.
Other solution: with some Java-drivers you can define several databases 
and checks (if the database read-only or rw), the next PostgreSQL 10 
will offer a similar feature.


PS.: please don't top-posting.


Regards, Andreas

--
2ndQuadrant - The PostgreSQL Support Company.
www.2ndQuadrant.com



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Re: [GENERAL] cluster question

[Alex Samad]

Hi

Quick question.  I have a 2 node cluster - each node has its own ip.

But from reading this, I really need a 3rd ip, which potentially floats
between the nodes to which ever is the master / rw node.

Is that right? Sort of makes sense I guess

A

On 14 August 2017 at 16:47, Andreas Kretschmer 
wrote:

> On 14 August 2017 08:39:54 GMT+02:00, Alex Samad 
> wrote:
> >Hi
> >
> >I have setup a streaming replicating cluster, with a hot standby.
> >
> >Now I would like to change the RW to hot standby and change the hot
> >standby
> >to be the RW server.
> >
> >Is it just a matter of updating recover.conf file ?
> >
> >Alex
>
> I would suggest you repmgr, with this tool you can do "repmgr standby
> switchover" to perform such tasks.
>
> Regards, Andreas.
>
>
> --
> 2ndQuadrant - The PostgreSQL Support Company
>

Re: [GENERAL] cluster question

[Andreas Kretschmer]

On 14 August 2017 08:39:54 GMT+02:00, Alex Samad  wrote:
>Hi
>
>I have setup a streaming replicating cluster, with a hot standby.
>
>Now I would like to change the RW to hot standby and change the hot
>standby
>to be the RW server.
>
>Is it just a matter of updating recover.conf file ?
>
>Alex

I would suggest you repmgr, with this tool you can do "repmgr standby 
switchover" to perform such tasks.

Regards, Andreas.


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