[pgpool-general: 4509] Re: pgpool unable to attach a node during failback command

[Tatsuo Ishii]

> OK....Thanks!
> 
> I'm trying to implement an failover/failback on the nodes:
> 1. primary node gets down.
> 2. pgpool promotes the secondary node - make it primary.
> 3. by attaching the failed node (old primary) -  the failback.sh is called
> and recovering the failed node (using rsync - much more faster) and make it
> online secondary!

I don't know what failback.sh is doing but if it just runs rsync, it's
not safe.  You should use pg_start_backup()/pg_stop_backup().

BTW, if rsync is much faster for you, why don't you use it for online
recovery as well?

> from what you are saying...
> just to make sure, I *can not* use the failback.sh script (which called by
> pcp_attach_node) in order "recover" the node and make it online (as
> scondary).

Ok, but failback.sh is not supposed to do what you want.
I recommend you to look into follow master command.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp

> Thanks,
> cohavisi
> 
> On Tue, Mar 1, 2016 at 2:15 PM, Tatsuo Ishii <ishii at postgresql.org> wrote:
> 
>> I'm not sure what you want to do (especialy I'm confused by
>> "secondary": what does it mean?). Have you taken look at follow master
>> script?
>>
>> Anyway...
>>
>> pcp_attach_node should be used for the case PostgreSQL server is
>> online and ready to use. Not for recovering a PostgreSQL server.
>>
>> Best regards,
>> --
>> Tatsuo Ishii
>> SRA OSS, Inc. Japan
>> English: http://www.sraoss.co.jp/index_en.php
>> Japanese:http://www.sraoss.co.jp
>>
>> > Hi,
>> > Thanks for your replay...
>> > I do use online recovery in case a full recovery is needed (using
>> > pg_basebackup - via pcp_recovery_node).
>> > but I added an ability to perform a switchover between the nodes using
>> > stop/detach primary - failover occurs and reattach it as secondary (using
>> > failback script).
>> > but as the failback finished the pgpool does not attach it as secondary!!
>> >
>> >
>> > Can you please advice?
>> >
>> > cohavisi
>> >
>> >
>> > On Tue, Mar 1, 2016 at 10:41 AM, Tatsuo Ishii <ishii at postgresql.org>
>> wrote:
>> >
>> >> You should use online recovery instead of pcp_attach_node.
>> >>
>> >> Best regards,
>> >> --
>> >> Tatsuo Ishii
>> >> SRA OSS, Inc. Japan
>> >> English: http://www.sraoss.co.jp/index_en.php
>> >> Japanese:http://www.sraoss.co.jp
>> >>
>> >> > Hi,
>> >> > I have a Hugh problem regarding attaching a node (as secondary) to the
>> >> pool
>> >> > after I performing pcp_attach_node.
>> >> >
>> >> > after failover is being completed successfully and valid primary node
>> is
>> >> > active, i'm performing an *pcp_attach (via sql)* to the faulty node in
>> >> > order to failback as secondary!
>> >> >
>> >> > *select pcp_attach_node (0,'10.10.61.99',1200,9898,'*****','*****') *
>> >> >
>> >> > during this command, a failback script is being executed and performs
>> the
>> >> > following:
>> >> > 1. rsync between the DB nodes.
>> >> > 2. create recovery.conf.
>> >> > 3. startup the node(as secondary).
>> >> >
>> >> > *the failback could take for 20 min to finish.*
>> >> >
>> >> > after the failback finished *successfully* (exit status 0) and the
>> node
>> >> > started as *secondary* (according to postgres) - streaming
>> replication.
>> >> >
>> >> > *the pgpool reportes the node status from 1 to 3 (instead of 2).*
>> >> >
>> >> > *** when failback finished early (less then few min) the pgpool
>> reports
>> >> the
>> >> > node status as 2 - as aspected.*
>> >> >
>> >> >
>> >> > please advice regarding this issue...
>> >> >
>> >> >
>> >> > *Thanks,*
>> >> > *cohavisi*
>> >>
>>