[Pgpool-general] replication/failover feature in Master/Slavemode

[Sandeep Thakkar]

Well, it was not working for me because I had not set health_check_period to 
some non zero value. When I set this to "4", it works fine. Failover is 
successful. Thanks for your help. BTW, what is good value for 
"health_check_period" ?






________________________________
From: "Daniel.Crespo at l-3com.com" <Daniel.Crespo at l-3com.com>
To: Armin Nesiren <armin.nesiren at intera.si>
Cc: sandeeptt at yahoo.com; pgpool-general at pgfoundry.org; Tatsuo Ishii 
<ishii at sraoss.co.jp>
Sent: Sat, January 29, 2011 3:30:18 AM
Subject: RE: RE: [Pgpool-general] replication/failover feature in 
Master/Slavemode

 
Try running pgpool -d -n, and search for “failover_command”. It should tell you 
if was or not executed. Remember to enable health_check in pgpool.conf. Search 
for “health_check” param in pgpool.conf.
 
-Daniel
 
From:Armin Nesiren [mailto:armin.nesiren at intera.si] 
Sent: Friday, January 28, 2011 4:01 PM
To: Crespo, Daniel @ SSG - SDS
Cc: sandeeptt at yahoo.com; pgpool-general at pgfoundry.org; Tatsuo Ishii
Subject: Re: RE: [Pgpool-general] replication/failover feature in 
Master/Slavemode
 
In my case there is no missunderstunding... 
Again... when I try to recover my old primary node (node 0) failover_command is 
not executed at all.
I'm testing it just like you have described...im trying to echo string in file 
that is located in /tmp
On 28 Jan 2011 21:55, <Daniel.Crespo at l-3com.com> wrote:
> I think there is a misunderstanding...
> 
> To clarify (just in case).
> 
> 1. Pgpool detects non-healthy postgresql backend.
> 2. Pgpool executes WHATEVER is in "failover_command" entry in
> pgpool.conf
> 3. The end.
> 
> In "failover_command" you can put
> "executeFailoverOfMyCurrentSlavePostgreSqlBackend.sh".
> Which means, in yout pgpool.conf you should have:
> failover_command="/path/to/executeFailoverOfMyCurrentSlavePostgreSqlBack
> end.sh"
> 
> in which you should do something like:
> 
> +++++++++++++++++
> #!/bin/bash
> 
> touch /path/to/where/trigger/file/must/exist
> 
> +++++++++++++++++
> 
> Of course, you'll want to touch the trigger file of the backend that is
> the standby, so you got to know its path. If you don't know it, let us
> know.
> 
> You might want to try having failover_command execute something that
> writes to /tmp/somefile to prove that pgpool is actually executing
> failover_command.
> 
> Best regards,
> -Daniel
> 
>> -----Original Message-----
>> From: Tatsuo Ishii [mailto:ishii at sraoss.co.jp]
>> Sent: Friday, January 28, 2011 9:21 AM
>> To: armin.nesiren at intera.si
>> Cc: sandeeptt at yahoo.com; ishii at sraoss.co.jp; Crespo, Daniel @ SSG -
>> SDS; pgpool-general at pgfoundry.org
>> Subject: Re: [Pgpool-general] replication/failover feature in
>> Master/Slavemode
>> 
>> > Also I have same problem.
>> > When I do pcp_recovery of my old primary node (node 0),
>> failover_command is
>> > not executed,
>> 
>> If you are using 3.0.x, then it's a known problem.
>> Please try CVS HEAD (to be released as 3.1).
>> --
>> Tatsuo Ishii
>> SRA OSS, Inc. Japan
>> English: http://www.sraoss.co.jp/index_en.php
>> Japanese: http://www.sraoss.co.jp
>> 
>> > I have set failback_command, and that command creates trigger file
>> for me.
>> >
>> > This configuration works fine right now, but I would like to know if
>> this is
>> > right way to do it?
>> >
>> > On Fri, Jan 28, 2011 at 12:53 PM, Sandeep Thakkar
>> <sandeeptt at yahoo.com>wrote:
>> >
>> >> Well, that's what my first question was. Why pgpool is not
> executing
>> the
>> >> failover_command in my case? Does it need any more settings in
>> pgpool.conf?
>> >> I did not set failback_command.
>> >>
>> >>
>> >>
>> >> ------------------------------
>> >> *From:* Tatsuo Ishii <ishii at sraoss.co.jp>
>> >> *To:* sandeeptt at yahoo.com
>> >> *Cc:* Daniel.Crespo at l-3com.com; guillaume at lelarge.info;
>> >> pgpool-general at pgfoundry.org
>> >> *Sent:* Fri, January 28, 2011 2:01:50 PM
>> >>
>> >> *Subject:* Re: [Pgpool-general] replication/failover feature in
>> >> Master/Slavemode
>> >>
>> >> No. Failover_command will be automatically executed by pgpool-II if
>> >> primary goes down. And you can have touch command to create the
>> >> trigger file in your failover_command. This should automatically
>> >> promote the standby.
>> >> --
>> >> Tatsuo Ishii
>> >> SRA OSS, Inc. Japan
>> >> English: http://www.sraoss.co.jp/index_en.php
>> >> Japanese: http://www.sraoss.co.jp
>> >>
>> >> > Thanks Tatsuo. So, does it mean with existing PG version (9.0),
> we
>> need
>> >> to
>> >> > manually execute failover script (create trigger file) even when
>> using
>> >> pgpool?
>> >> >
>> >> >
>> >> >
>> >> >
>> >> > ________________________________
>> >> > From: Tatsuo Ishii <ishii at sraoss.co.jp>
>> >> > To: sandeeptt at yahoo.com
>> >> > Cc: Daniel.Crespo at l-3com.com; guillaume at lelarge.info;
>> >> > pgpool-general at pgfoundry.org
>> >> > Sent: Fri, January 28, 2011 1:08:08 PM
>> >> > Subject: Re: [Pgpool-general] replication/failover feature in
>> >> Master/Slavemode
>> >> >
>> >> >> Yes, I'm aware that I need to create a trigger file (same as
> what
>> is
>> >> defined in
>> >> >>
>> >> >> recovery.conf) to start the failover and promote the Standby to
>> Primary.
>> >> I have
>> >> >>
>> >> >> tried this when I did not use pgpool and it worked fine. I
>> thought, when
>> >> pgpool
>> >> >>
>> >> >> is in picture, it will execute the failver_command, when it
>> detects that
>> >>
>> >> >>primary
>> >> >>
>> >> >> is down. and since, the failover_command in my case is to "touch
>> trigger
>> >> file".
>> >> >>
>> >> >> Shouldn't pgpool execute the failover_command here and create
>> that file
>> >> >> automatically?
>> >> >
>> >> > Besides the problem that it's not easy to read and parse
>> >> > recovery.conf, creating trigger file might not be the only way to
>> >> > promote standby server forever. Actually currently PostgreSQL
>> >> > developers are discussing about "pg_ctl failover" command which
>> will
>> >> > be a new way to promote standby in the next version of
>> >> > PostgreSQL. Pgpool-II is designed to be flexible to work with as
>> many
>> >> > PostgreSQL version as possible. So we don't want to hard code
>> "touch
>> >> > trigger file" in pgpool itself.
>> >> >
>> >> >> I think, either pgpool is not able to detect that primary is
> down
>> >> >> or it is unable to execute the failover_command. Am I missing to
>> define
>> >> >>anything
>> >> >>
>> >> >> in the configuration file?
>> >>
>> >>
>> >>
>> >> _______________________________________________
>> >> Pgpool-general mailing list
>> >> Pgpool-general at pgfoundry.org
>> >> http://pgfoundry.org/mailman/listinfo/pgpool-general
>> >>
>> >>
>> >
>> >
>> > --
>> > Armin


      
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