From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f44.google.com ([74.125.82.44]:37360 "EHLO mail-wm0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750775AbbLaJBz (ORCPT ); Thu, 31 Dec 2015 04:01:55 -0500 Received: by mail-wm0-f44.google.com with SMTP id f206so104735746wmf.0 for ; Thu, 31 Dec 2015 01:01:54 -0800 (PST) Received: from orione.localnet (183.Red-83-50-202.dynamicIP.rima-tde.net. [83.50.202.183]) by smtp.gmail.com with ESMTPSA id e62sm60615550wma.11.2015.12.31.01.01.52 for (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 31 Dec 2015 01:01:53 -0800 (PST) From: =?ISO-8859-1?Q?fugazzi=AE?= To: Btrfs mailing list Subject: BTRFS - Write Barriers Date: Thu, 31 Dec 2015 09:01:51 +0000 Message-ID: <4794805.EoAJ2iVUQK@orione> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hi everyone :-) Just one question for the gurus here. I was wondering: if I disable write barriers in btrfs with the mount option nobarrier I just disable the periodic flushes of the hardware disk cache or I'm disabling also the order of the writes directed to the hard disk? What I mean is: is it safe to disable write barrier with a UPS with which I will likely have the hardware always powered even in the event of a kernel crash, freeze, etc? I'm asking because if also the ordering of the write is no more guaranteed I guess it would not be safe to disable write barrier even if the possibility of an unexpected power down of the HD was remote because in the case of a crash the order of the write would be messed up anyway and we could boot up with a completely corrupted fs. Thank you very much for your kinds answers. Warm Regards, Mario