From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751107AbWHBDwJ (ORCPT ); Tue, 1 Aug 2006 23:52:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751111AbWHBDwJ (ORCPT ); Tue, 1 Aug 2006 23:52:09 -0400 Received: from 63-162-81-179.lisco.net ([63.162.81.179]:45530 "EHLO grunt.slaphack.com") by vger.kernel.org with ESMTP id S1751107AbWHBDwI (ORCPT ); Tue, 1 Aug 2006 23:52:08 -0400 Message-ID: <44D02166.7070406@slaphack.com> Date: Tue, 01 Aug 2006 23:52:06 -0400 From: David Masover User-Agent: Thunderbird 1.5.0.5 (Macintosh/20060719) MIME-Version: 1.0 To: Ian Stirling CC: David Lang , Nate Diller , Adrian Ulrich , "Horst H. von Brand" , ipso@snappymail.ca, reiser@namesys.com, lkml@lpbproductions.com, jeff@garzik.org, tytso@mit.edu, linux-kernel@vger.kernel.org, reiserfs-list@namesys.com Subject: Re: Solaris ZFS on Linux [Was: Re: the " 'official' point of view"expressed by kernelnewbies.org regarding reiser4 inclusion] References: <20060731175958.1626513b.reiser4@blinkenlights.ch> <200607311918.k6VJIqTN011066@laptop13.inf.utfsm.cl> <20060731225734.ecf5eb4d.reiser4@blinkenlights.ch> <44CE7C31.5090402@gmx.de> <5c49b0ed0607311621i54f1c46fh9137f8955c9ea4be@mail.gmail.com> <5c49b0ed0607311650j4b86d0c3h853578f58db16140@mail.gmail.com> <5c49b0ed0607311705t1eb8fc6bs9a68a43059bfa91a@mail.gmail.com> <20060801010215.GA24946@merlin.emma.line.org> <44CEAEF4.9070100@slaphack.com> <44CED95C.10709@slaphack.com> <44CFE8D9.9090606@mauve.plus.com> In-Reply-To: <44CFE8D9.9090606@mauve.plus.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Ian Stirling wrote: > David Masover wrote: >> David Lang wrote: >> >>> On Mon, 31 Jul 2006, David Masover wrote: >>> >>>> Oh, I'm curious -- do hard drives ever carry enough >>>> battery/capacitance to cover their caches? It doesn't seem like it >>>> would be that hard/expensive, and if it is done that way, then I >>>> think it's valid to leave them on. You could just say that other >>>> filesystems aren't taking as much advantage of newer drive features >>>> as Reiser :P >>> >>> >>> there are no drives that have the ability to flush their cache after >>> they loose power. >> >> >> Aha, so back to the usual argument: UPS! It takes a fraction of a >> second to flush that cache. > > You probably don't actually want to flush the cache - but to write > to a journal. > 16M of cache - split into 32000 writes to single sectors spread over > the disk could well take several minutes to write. Slapping it onto > a journal would take well under .2 seconds. > That's a non-trivial amount of storage though - 3J or so, 40mF@12V - > a moderately large/expensive capacitor. Before we get ahead of ourselves, remember: ~$200 buys you a huge amount of battery storage. We're talking several minutes for several boxes, at the very least -- more like 10 minutes. But yes, a journal or a software suspend.