From: Chris Mason Subject: Re: [PATCH 0/4] (RESEND) ext3[34] barrier changes Date: Wed, 21 May 2008 15:40:35 -0400 Message-ID: <200805211540.36276.chris.mason@oracle.com> References: <482DDA56.6000301@redhat.com> <20080521182949.GL8581@mit.edu> <20080521193633.GA26780@shareable.org> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: Theodore Tso , Andrew Morton , Pavel Machek , Eric Sandeen , Andi Kleen , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org To: Jamie Lokier Return-path: In-Reply-To: <20080521193633.GA26780@shareable.org> Content-Disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Wednesday 21 May 2008, Jamie Lokier wrote: > Theodore Tso wrote: > > On Wed, May 21, 2008 at 11:03:24AM -0700, Andrew Morton wrote: > > > afaik there is no need to enable this feature if the machine (actually > > > the disks) are on a UPS, yes? > > > > Yes, as long as you're confident that there won't be a kernel > > bug/regression causing a lockup while the server is under severe > > memory pressure while doing lots of fsync's, file creations, renames, > > etc. And as long as your 100% confident that UPS's will never fail, > > janitors will never accidentally hit the Emergency Power Office > > Can a kernel lockup cause this kind of corruption? No > > Will a system reboot wipe the disk's write cache? > Only if you reboot with the power switch (some test rigs do) > I had imagined only power loss would prevent the disk from > writing it's cache eventually; is that wrong? > -chris