From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030211AbVI1H56 (ORCPT ); Wed, 28 Sep 2005 03:57:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030212AbVI1H56 (ORCPT ); Wed, 28 Sep 2005 03:57:58 -0400 Received: from h80ad25b8.async.vt.edu ([128.173.37.184]:64974 "EHLO h80ad25b8.async.vt.edu") by vger.kernel.org with ESMTP id S1030211AbVI1H55 (ORCPT ); Wed, 28 Sep 2005 03:57:57 -0400 Message-Id: <200509280757.j8S7vmjB023730@turing-police.cc.vt.edu> X-Mailer: exmh version 2.7.2 01/07/2005 with nmh-1.1-RC3 To: iodophlymiaelo@gmail.com Cc: linux-kernel@vger.kernel.org Subject: Re: raw aio write guarantee In-Reply-To: Your message of "Wed, 28 Sep 2005 00:12:33 PDT." <98b62faa050928001275d28771@mail.gmail.com> From: Valdis.Kletnieks@vt.edu References: <98b62faa050928001275d28771@mail.gmail.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1127894267_31960P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Wed, 28 Sep 2005 03:57:47 -0400 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --==_Exmh_1127894267_31960P Content-Type: text/plain; charset=us-ascii On Wed, 28 Sep 2005 00:12:33 PDT, iodophlymiaelo@gmail.com said: > Just a quick question: How can a user-mode application ensure that an > AIO write on a raw block device (i.e. open()ed with O_DIRECT) has > really -really- been written to the disk and not residing in an on-disk > write cache where it could be lost in case of a power failure? Step 1: Make sure you buy disk drives that don't lie through their teeth regarding details such as "is the write cache enabled?" or "did the flush cache work?". Such hardware can generate vast amounts of bad karma.... Step 2: Buy a UPS. A good one. You can't lose the cache during a power failure that doesn't actually hit. Step 3: http://catb.org/~esr/jargon/html/M/molly-guard.html - You want these. Lots of them. --==_Exmh_1127894267_31960P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (GNU/Linux) Comment: Exmh version 2.5 07/13/2001 iD8DBQFDOkz7cC3lWbTT17ARAsIrAKCFjVEouw1nnDfUNpTp1KTHm9yfGQCeLtiA v3aokm7d99PnrWqc+zrjJK0= =aTF+ -----END PGP SIGNATURE----- --==_Exmh_1127894267_31960P--