[pgpool-general: 2936] Re: pool members are reporting different backend states
Attila Heidrich
attila.heidrich at gmail.com
Fri Jun 20 17:00:04 JST 2014
Postgres can stop. So does the Linux, or the hardware. Network connection
can be lost. You can blame me, but this is the real life.
This is why we use more than one of them.
If Pg stops, still I'm sure that backend status must reflect this in all
the pool members!
Even if a single pool cannot reach the backend, it should notify all others
not to use that backend, or say good bye to your consistent database!
So finally: is there any status information what's shared among pool
members? What is it, if not the backend database status?
Attila
2014-06-20 9:47 GMT+02:00 Tatsuo Ishii <ishii at postgresql.org>:
> Attila,
>
> If you restart pgpool-II and the backend status which pgpool-II
> recognizes is different from actual PostgreSQL's staus, then it is
> likely that you stop or restart PostgreSQL between pgpool-II stops and
> restarts. In another other word, you directly changed backend situation
> without let pgpool-II notices it. i.e. your fault.
>
> Best regards,
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese:http://www.sraoss.co.jp
>
> > Yep, "service pgpool2 force-reload" has corrected this, but I am not
> happy
> > at all.
> >
> > I thought that the pool status is consistent among the members. If pgpool
> > does the replication, it is a disaster to have different backend sets in
> > the pool members!
> > No way to keep databases consistent... One pool will write just one
> > backend, the other will write both.
> >
> > Attila
> >
> >
> > 2014-06-19 12:08 GMT+02:00 Yugo Nagata <nagata at sraoss.co.jp>:
> >
> >> Hi,
> >>
> >> On Thu, 19 Jun 2014 11:05:32 +0200
> >> Attila Heidrich <attila.heidrich at gmail.com> wrote:
> >>
> >> > Dear Guys,
> >> >
> >> > How on earth it is possible, that the pool members reports different
> >> > backend status? It will cause problems very soon I guess.
> >>
> >> It is possible if pgpool reads old backend status info when this starts
> up.
> >> pgpool will discard the old backend info when starts with -D option.
> >>
> >> However, it would be better pgpools can detect the status mismatch
> >> between them in some way.
> >>
> >> >
> >> > Node: 1
> >> > Host: 10.100.1.11
> >> > Port: 5433
> >> > Weight: 0.500000
> >> > Status: Up, in pool (1)
> >> > WD status: Standby (2)
> >> >
> >> > Node: 2
> >> > Host: 10.100.1.10
> >> > Port: 5433
> >> > Weight: 0.500000
> >> > Status: Up, in pool (1)
> >> >
> >> > ---
> >> >
> >> > Node: 1
> >> > Host: 10.100.1.11
> >> > Port: 5433
> >> > Weight: 0.500000
> >> > Status: Up, detached from pool (3)
> >> > WD status: Standby (2)
> >> >
> >> > Node: 2
> >> > Host: 10.100.1.10
> >> > Port: 5433
> >> > Weight: 0.500000
> >> > Status: Up, in pool (1)
> >> > WD status: Standby (2)
> >> >
> >> > ---
> >> >
> >> > Node: 1
> >> > Host: 10.100.1.11
> >> > Port: 5433
> >> > Weight: 0.500000
> >> > Status: Up, in pool (1)
> >> > WD status: Standby (2)
> >> >
> >> > Node: 2
> >> > Host: 10.100.1.10
> >> > Port: 5433
> >> > Weight: 0.500000
> >> > Status: Up, in pool (1)
> >> > WD status: Active (3)
> >> >
> >> > ---
> >> >
> >> > Node: 1
> >> > Host: 10.100.1.11
> >> > Port: 5433
> >> > Weight: 0.500000
> >> > Status: Up, in pool (1)
> >> > WD status: Standby (2)
> >> >
> >> > Node: 2
> >> > Host: 10.100.1.10
> >> > Port: 5433
> >> > Weight: 0.500000
> >> > Status: Up, in pool (1)
> >> > WD status: Standby (2)
> >> >
> >> > ---
> >> >
> >> > Node: 1
> >> > Host: 10.100.1.11
> >> > Port: 5433
> >> > Weight: 0.500000
> >> > Status: Up, detached from pool (3)
> >> > WD status: Standby (2)
> >> >
> >> > Node: 2
> >> > Host: 10.100.1.10
> >> > Port: 5433
> >> > Weight: 0.500000
> >> > Status: Up, in pool (1)
> >> > WD status: Active (3)
> >> >
> >> > I have got five pool members, two of them are the backends themselves.
> >> >
> >> > Every pool member has the other 4 as other_pgpool, and
> >> > heartbeat_destination, and the same two backend servers, here is the
> >> > relevant part of the config for all pool members:
> >> >
> >> >
> >> > nor-openfire-1:
> >> > backend_hostname1 = '10.100.1.11'
> >> > backend_port1 = 5433
> >> > backend_weight1 = 1
> >> > backend_data_directory1 = '/var/lib/postgresql/9.3'
> >> > backend_flag1 = 'ALLOW_TO_FAILOVER'
> >> > backend_hostname2 = '10.100.1.10'
> >> > backend_port2 = 5433
> >> > backend_weight2 = 1
> >> > backend_data_directory2 = '/var/lib/postgresql/9.3'
> >> > backend_flag2 = 'ALLOW_TO_FAILOVER'
> >> > fail_over_on_backend_error = on
> >> > heartbeat_destination0 = 'nor-postgres-2'
> >> > heartbeat_destination_port0 = 9694
> >> > other_pgpool_hostname0 = 'nor-postgres-2'
> >> > other_pgpool_port0 = 5432
> >> > heartbeat_destination1 = 'nor-jboss-2'
> >> > heartbeat_destination_port1 = 9694
> >> > other_pgpool_hostname1 = 'nor-jboss-2'
> >> > other_pgpool_port1 = 5432
> >> > heartbeat_destination2 = 'nor-postgres-1'
> >> > heartbeat_destination_port2 = 9694
> >> > other_pgpool_hostname2 = 'nor-postgres-1'
> >> > other_pgpool_port2 = 5432
> >> > heartbeat_destination3 = 'nor-jboss-1'
> >> > heartbeat_destination_port3 = 9694
> >> > other_pgpool_hostname3 = 'nor-jboss-1'
> >> > other_pgpool_port3 = 5432
> >> > nor-postgres-1:
> >> > backend_hostname1 = '10.100.1.11'
> >> > backend_port1 = 5433
> >> > backend_weight1 = 1
> >> > backend_data_directory1 = '/var/lib/postgresql/9.3'
> >> > backend_flag1 = 'ALLOW_TO_FAILOVER'
> >> > backend_hostname2 = '10.100.1.10'
> >> > backend_port2 = 5433
> >> > backend_weight2 = 1
> >> > backend_data_directory2 = '/var/lib/postgresql/9.3'
> >> > backend_flag2 = 'ALLOW_TO_FAILOVER'
> >> > fail_over_on_backend_error = on
> >> > heartbeat_destination0 = 'nor-postgres-2'
> >> > heartbeat_destination_port0 = 9694
> >> > other_pgpool_hostname0 = 'nor-postgres-2'
> >> > other_pgpool_port0 = 5432
> >> > heartbeat_destination1 = 'nor-jboss-2'
> >> > heartbeat_destination_port1 = 9694
> >> > other_pgpool_hostname1 = 'nor-jboss-2'
> >> > other_pgpool_port1 = 5432
> >> > heartbeat_destination2 = 'nor-openfire-1'
> >> > heartbeat_destination_port2 = 9694
> >> > other_pgpool_hostname2 = 'nor-openfire-1'
> >> > other_pgpool_port2 = 5432
> >> > heartbeat_destination3 = 'nor-jboss-1'
> >> > heartbeat_destination_port3 = 9694
> >> > other_pgpool_hostname3 = 'nor-jboss-1'
> >> > other_pgpool_port3 = 5432
> >> > nor-postgres-2:
> >> > backend_hostname1 = '10.100.1.11'
> >> > backend_port1 = 5433
> >> > backend_weight1 = 1
> >> > backend_data_directory1 = '/var/lib/postgresql/9.3'
> >> > backend_flag1 = 'ALLOW_TO_FAILOVER'
> >> > backend_hostname2 = '10.100.1.10'
> >> > backend_port2 = 5433
> >> > backend_weight2 = 1
> >> > backend_data_directory2 = '/var/lib/postgresql/9.3'
> >> > backend_flag2 = 'ALLOW_TO_FAILOVER'
> >> > fail_over_on_backend_error = on
> >> > heartbeat_destination0 = 'nor-jboss-2'
> >> > heartbeat_destination_port0 = 9694
> >> > other_pgpool_hostname0 = 'nor-jboss-2'
> >> > other_pgpool_port0 = 5432
> >> > heartbeat_destination1 = 'nor-openfire-1'
> >> > heartbeat_destination_port1 = 9694
> >> > other_pgpool_hostname1 = 'nor-openfire-1'
> >> > other_pgpool_port1 = 5432
> >> > heartbeat_destination2 = 'nor-postgres-1'
> >> > heartbeat_destination_port2 = 9694
> >> > other_pgpool_hostname2 = 'nor-postgres-1'
> >> > other_pgpool_port2 = 5432
> >> > heartbeat_destination3 = 'nor-jboss-1'
> >> > heartbeat_destination_port3 = 9694
> >> > other_pgpool_hostname3 = 'nor-jboss-1'
> >> > other_pgpool_port3 = 5432
> >> > nor-jboss-1:
> >> > backend_hostname1 = '10.100.1.11'
> >> > backend_port1 = 5433
> >> > backend_weight1 = 1
> >> > backend_data_directory1 = '/var/lib/postgresql/9.3'
> >> > backend_flag1 = 'ALLOW_TO_FAILOVER'
> >> > backend_hostname2 = '10.100.1.10'
> >> > backend_port2 = 5433
> >> > backend_weight2 = 1
> >> > backend_data_directory2 = '/var/lib/postgresql/9.3'
> >> > backend_flag2 = 'ALLOW_TO_FAILOVER'
> >> > fail_over_on_backend_error = on
> >> > heartbeat_destination0 = 'nor-postgres-2'
> >> > heartbeat_destination_port0 = 9694
> >> > other_pgpool_hostname0 = 'nor-postgres-2'
> >> > other_pgpool_port0 = 5432
> >> > heartbeat_destination1 = 'nor-jboss-2'
> >> > heartbeat_destination_port1 = 9694
> >> > other_pgpool_hostname1 = 'nor-jboss-2'
> >> > other_pgpool_port1 = 5432
> >> > heartbeat_destination2 = 'nor-openfire-1'
> >> > heartbeat_destination_port2 = 9694
> >> > other_pgpool_hostname2 = 'nor-openfire-1'
> >> > other_pgpool_port2 = 5432
> >> > heartbeat_destination3 = 'nor-postgres-1'
> >> > heartbeat_destination_port3 = 9694
> >> > other_pgpool_hostname3 = 'nor-postgres-1'
> >> > other_pgpool_port3 = 5432
> >> > nor-jboss-2:
> >> > backend_hostname1 = '10.100.1.11'
> >> > backend_port1 = 5433
> >> > backend_weight1 = 1
> >> > backend_data_directory1 = '/var/lib/postgresql/9.3'
> >> > backend_flag1 = 'ALLOW_TO_FAILOVER'
> >> > backend_hostname2 = '10.100.1.10'
> >> > backend_port2 = 5433
> >> > backend_weight2 = 1
> >> > backend_data_directory2 = '/var/lib/postgresql/9.3'
> >> > backend_flag2 = 'ALLOW_TO_FAILOVER'
> >> > fail_over_on_backend_error = on
> >> > heartbeat_destination0 = 'nor-postgres-2'
> >> > heartbeat_destination_port0 = 9694
> >> > other_pgpool_hostname0 = 'nor-postgres-2'
> >> > other_pgpool_port0 = 5432
> >> > heartbeat_destination1 = 'nor-openfire-1'
> >> > heartbeat_destination_port1 = 9694
> >> > other_pgpool_hostname1 = 'nor-openfire-1'
> >> > other_pgpool_port1 = 5432
> >> > heartbeat_destination2 = 'nor-postgres-1'
> >> > heartbeat_destination_port2 = 9694
> >> > other_pgpool_hostname2 = 'nor-postgres-1'
> >> > other_pgpool_port2 = 5432
> >> > heartbeat_destination3 = 'nor-jboss-1'
> >> > heartbeat_destination_port3 = 9694
> >> > other_pgpool_hostname3 = 'nor-jboss-1'
> >> > other_pgpool_port3 = 5432
> >> >
> >> > Other question:
> >> >
> >> > Our servers are connected via two networks. Is it possible to specify
> a
> >> > pool member with both IP interfaces?
> >>
> >> One other pgpool must be specified by single IP or hostname. You can use
> >> either
> >> of them. The exception is heartbeat destination; you can specify both IP
> >> as heartbeat_destinationX.
> >>
> >> >
> >> >
> >>
> ----------------------------------------------------------------------------------------
> >> > Network #1
> >> > | | | |
> >> > |
> >> > S1 S2 S3 S4
> >> S5
> >> > | | | |
> >> > |
> >> >
> >>
> ----------------------------------------------------------------------------------------
> >> > Network #2
> >> >
> >> > none of the networks are connected with failover connections, both use
> >> > different IP subnets.
> >> >
> >> > Regards,
> >> >
> >> > Attila
> >>
> >>
> >> --
> >> Yugo Nagata <nagata at sraoss.co.jp>
> >>
>
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