Message-ID: <4CBDAF58.9050503@nrc-cnrc.gc.ca>
Date: Tue, 19 Oct 2010 07:46:48 -0700
From: Isabella Ghiurea <isabella.ghiurea@nrc-cnrc.gc.ca>
Reply-To: isabella.ghiurea@nrc-cnrc.gc.ca
Organization: CADC -NRC
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To: Fujii Masao <masao.fujii@gmail.com>
CC: "pgsql-admin@postgresql.org" <pgsql-admin@postgresql.org>
Subject: Re: WAL log shipping + Streaming replication PG 9.0 questions
References: <4CBC8886.9040608@nrc-cnrc.gc.ca>
	<AANLkTi=DHscwip3JhGOSPBA9H_VcqHHFjdJy5Bomj2Tv@mail.gmail.com>
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Fujii Masao wrote:
> On Tue, Oct 19, 2010 at 2:48 AM, Isabella Ghiurea
> <isabella.ghiurea@nrc-cnrc.gc.ca> wrote:
>   
>> I have some questions regarding hot standby  + streaming replication (PG
>> 9.0) : what is   master/primary  server  behavior if  archive_command fails
>>  due to  archive  directory off line/unavailable?
>>     
>
> Unarchived WAL files continue to accumulate in pg_xlog directory while
> the archive directory is unavailable. Then, if pg_xlog directory is
> filled up, the PostgreSQL server causes the PANIC error.
>
>   
>> How about standby server  behavior if restore command fails due to
>> archive_master directory not available?
>>     
>
> After restore_command fails, the standby tries to read WAL file from
> its pg_xlog directory. And, if there is no WAL file to recover in pg_xlog,
> the standby tries to connect to the master and read the streamed WAL files
> from the master.
>
> Regards,
>
>   
Thank you for all details.
 For the last question I ' m still a bit confused: if master_archive off 
line ( no archived WAL's available) what will be state of  standby server ?
Basically we are trying to design a solution where WAL archived 
directory is not a "single point of failure"   for whole system ( we are 
planing to have WAL archived master directory on a separate machine and 
both server primary and standby will have read/write here) if this 
servers fails , we  want  to  be able to continue normal user operation 
on master while standby server  will have some latency.
Isabella


-- 
-----------------------------------------------------------
Isabella A. Ghiurea 

Isabella.Ghiurea@nrc-cnrc.gc.ca
Canadian Astronomy Data Centre |http://www.nrc-cnrc.gc.ca/eng/services/hia/data-centre.html 
National Research Council of Canada, Herzberg Institute of Astrophysics 
5071 West Saanich Road, Victoria BC V9E 2E7, Canada
Phone: 250 363-3446 fax: 250 363-0045