From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 24 Sep 2001 12:53:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 24 Sep 2001 12:52:46 -0400 Received: from krusty.E-Technik.Uni-Dortmund.DE ([129.217.163.1]:42759 "HELO krusty.e-technik.uni-dortmund.de") by vger.kernel.org with SMTP id ; Mon, 24 Sep 2001 12:52:41 -0400 Date: Mon, 24 Sep 2001 18:53:03 +0200 From: Matthias Andree To: linux-kernel@vger.kernel.org, reiserfs-list@namesys.com Subject: Re: [PATCH] 2.4.10 improved reiserfs a lot, but could still be better Message-ID: <20010924185303.B10117@emma1.emma.line.org> Mail-Followup-To: linux-kernel@vger.kernel.org, reiserfs-list@namesys.com In-Reply-To: <20010924173210.A7630@emma1.emma.line.org> <20010924161518.KYHD11251.femail27.sdc1.sfba.home.com@there> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20010924161518.KYHD11251.femail27.sdc1.sfba.home.com@there> User-Agent: Mutt/1.3.22.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 24 Sep 2001, Nicholas Knight wrote: > > Turn it off (I have no idea of internals, but I presume it'll still > > be a write-through cache, so reading back will still be served from > > the buffer). Do hdparm -W0 /dev/hd[a-h]. > > I'm sorry, but that's not acceptable. > Please note the dd timings at the bottom of this message. Well, of course, turning off the cache will cause performance penalties, but it at least gives you a chance to get away with a recoverable file system should the power fail or the box crash. > Yes, a typical desktop user isn't going to notice much, even a normal > webserver or fileserver not dealing with constant updates may not, but > certain workloads will. These workloads are real enough that telling > people to disable write caching out of hand is a bad idea. I switched a box to ext3 with write caches off in expectance of multiple power outages during works, and NOTHING happened. I expect that box is now writing 4 times slower than before, I have no real figures, and it's still "smooth enough" in spite of 2.4.9. > Keep in mind also, that you may be putting your data and filesystems in > more risk by not using a write cache as with using it. Utterly non-sense. Linear writing as dd mostly does is BTW something which should never be affected by write caches. -- Matthias Andree "Those who give up essential liberties for temporary safety deserve neither liberty nor safety." - Benjamin Franklin