Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1YsvSD-0004VE-3v for pgsql-admin@arkaria.postgresql.org; Thu, 14 May 2015 15:53:45 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1YsvSC-000114-Kx for pgsql-admin@arkaria.postgresql.org; Thu, 14 May 2015 15:53:44 +0000 Received: from makus.postgresql.org ([2001:4800:1501:1::229]) by malur.postgresql.org with esmtps (TLS1.2:RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1YsvSB-00010w-QK for pgsql-admin@postgresql.org; Thu, 14 May 2015 15:53:43 +0000 Received: from momjian.us ([72.94.173.45]) by makus.postgresql.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.84) (envelope-from ) id 1YsvS9-0001UE-6p for pgsql-admin@postgresql.org; Thu, 14 May 2015 15:53:42 +0000 Received: from bruce by momjian.us with local (Exim 4.72) (envelope-from ) id 1YsvS6-0003bW-Oi; Thu, 14 May 2015 11:53:38 -0400 Date: Thu, 14 May 2015 11:53:38 -0400 From: Bruce Momjian To: Ravi Krishna Cc: tgl@sss.pgh.pa.us, pgsql-admin@postgresql.org Subject: Re: WAL and O_DIRECT Message-ID: <20150514155338.GA23739@momjian.us> References: <20588.1431616292@sss.pgh.pa.us> <14d530df35f-2108-30ce7@webstg-m03.mail.aol.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <14d530df35f-2108-30ce7@webstg-m03.mail.aol.com> User-Agent: Mutt/1.5.20 (2009-06-14) X-Pg-Spam-Score: -1.9 (-) List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-admin Precedence: bulk Sender: pgsql-admin-owner@postgresql.org On Thu, May 14, 2015 at 11:32:12AM -0400, Ravi Krishna wrote: > Aha that pretty much explains it. Yes we are using streaming replication. > > However our DB2 folks are raising a concern that PG WAL writes may not be crash > safe, unless we are using write back technology in SAN or SSD , which we are > using. We write WAL to the kernel, then issue fsync. -- Bruce Momjian http://momjian.us EnterpriseDB http://enterprisedb.com + Everyone has their own god. + -- Sent via pgsql-admin mailing list (pgsql-admin@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin