[Pgpool-general] failback setup problem

[Tatsuo Ishii]

You mean the pgpool parent process? It won't restart by failover or
any pcp command. BTW pgpool main process source code is main.c.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp

> "After failback_command finishes, pgpool-II restart all child   processes." . 
> How about the pgpool server process (pgpool -d -D)? Does it also get affected 
> when I execute pcp_recovery_node? I would like to see this source code..  Which 
> files should I look into?
> 
> 
> Thanks.
> 
> 
> 
> 
> ________________________________
> From: Tatsuo Ishii <ishii at sraoss.co.jp>
> To: uwe.bartels at gmail.com
> Cc: pgpool-general at pgfoundry.org
> Sent: Sun, May 1, 2011 3:20:31 PM
> Subject: Re: [Pgpool-general] failback setup problem
> 
>>>> >> I'm not sure what you are trying to do here. If "backup" means it was
>>>> >> created by pg_dump_all, I don't think your approach works. Streaming
>>>> >> replication requires a base backup(binary backup) which is managed by
>>>> >> pg_start_backup/pg_stop_backup.
>>>> >>
>>>> >
>>>> > Yes of course I have a backup created as described in
>>>> >
>>>>http://www.postgresql.org/docs/9.0/static/continuous-archiving.html#BACKUP-BASE-BACKUP
>>>>P
>> 
>> If you keep wal archives along with the base backup, then it should be
>> possible to recover primary PostgreSQL from them of course. Question
>> is, how to recover standbys. In my understanding you need to recreate
>> them from the recovered primary anyway and it will require *new* base
>> backup.
>> 
>>>> > My question is, what happens if both server failed somehow? Can I still
>>>> use
>>>> > pgpoolAdmin to recover a database server?
>>>>
>>>> No, pgpoolAdmin cannot recover a database server in this situation.
>>>> You have to recover the database manualy.
>>>>
>>> Yes. I thought that of course.
>>> So my question was, if you leave the whole restore process up to one called
>>> recovery script - including optional checkpointing etc. pgpool would be more
>>> flexible and simplier in terms of supporting different recovery procedures.
>> 
>> Good question. I will inspect current code if your idea is possible
>> while updating docs.
> 
> Here are steps executed in recovery procedure (described in the updted
> doc today). Note that CHECK POINT is not performed in the procedure.
> If all PostgreSQL servers down case, you want to skip #1 and #2 and
> want to execute #3, #4, #5 by ssh. What do you think?
> 
>    1. Pgpool-II connects to primary server's template1 database as
>    user = recovery_user, password = recovery_password.
> 
>    2. Primary server executes pgpool_recovery function.
> 
>    3. pgpool_recovery function executes
>    recovery_1st_stage_command. Note that PostgreSQL executes functions
>    with database cluster as the current directory. Thus
>    recovery_1st_stage_command is executed in the database cluster
>    directory.
> 
>    4. Primary server executes pgpool_remote_start function. This
>    function executes a script named "pgpool_remote_start" in the
>    database cluster directory, and it executes pg_ctl command on the
>    standby server to be recovered via ssh. pg_ctl will start
>    postmaster in background. So we need to make sure that postmaster
>    on the standby actually starts.
> 
>    5. pgpool-II tries to connect to the standby PostgreSQL as user =
>    recovery_user and password = recovery_password. The database to be
>    connected is "postgres" if possible. Otherwise "template1" is
>    used. pgpool-II retries for recovery_timeout seconds. If success,
>    go to next step.
> 
>    6. If failback_command is not empty, pgpool-II parent process
>    executes the script.
> 
>    7. After failback_command finishes, pgpool-II restart all child
>    processes.
> 
>>> By he way - where does pgpool actually store the information about
>>> attached/detached servers?
>> 
>> On shared memory.
>> --
>> Tatsuo Ishii
>> SRA OSS, Inc. Japan
>> English: http://www.sraoss.co.jp/index_en.php
>> Japanese: http://www.sraoss.co.jp
>> _______________________________________________
>> Pgpool-general mailing list
>> Pgpool-general at pgfoundry.org
>> http://pgfoundry.org/mailman/listinfo/pgpool-general
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