From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.saout.de ([127.0.0.1]) by localhost (mail.saout.de [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id LxxeL-6kD496 for ; Tue, 20 Sep 2011 20:06:51 +0200 (CEST) Received: from smtp.meme.com (janus.meme.com [69.17.73.118]) by mail.saout.de (Postfix) with ESMTP for ; Tue, 20 Sep 2011 20:06:50 +0200 (CEST) Received: from mofo.meme.com (unknown [192.168.1.2]) by smtp.meme.com (Postfix) with ESMTP id 22FE7A0DE for ; Tue, 20 Sep 2011 13:06:48 -0500 (CDT) Received: from mofo (localhost.localdomain [127.0.0.1]) by mofo.meme.com (Postfix) with ESMTP id ECB5143D0F for ; Tue, 20 Sep 2011 13:06:47 -0500 (CDT) Date: Tue, 20 Sep 2011 13:06:47 -0500 From: "Karl O. Pinc" References: <1316515022.7965.31.camel@zarniwoop> <20110920114724.GA21251@tansi.org> <4E78AF92.9040309@alexanderkoch.net> <20110920174129.GA25723@tansi.org> In-Reply-To: <20110920174129.GA25723@tansi.org> (from arno@wagner.name on Tue Sep 20 12:41:29 2011) Message-Id: <1316542007.4663.0@mofo> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [dm-crypt] (More) Questions about LUKS / LVM List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: dm-crypt@saout.de On 09/20/2011 12:41:29 PM, Arno Wagner wrote: > On Tue, Sep 20, 2011 at 05:21:54PM +0200, Alexander Koch wrote: > > Am 20.09.2011 13:47, schrieb Arno Wagner: > > > With an SSD, things are a bit different. Due to the large > > > internal sector size, the header can be in a sector that > > > also has data that gets rewritten in it. As sectors are > > > always written completely, the header then is at risk whenever > > > that data gets rewritten. > No connection with TRIM support. It is just that if the real > block size is larger than the block size you are using, > the SSD will rewrite/reloacte other data on writes smaller > that the real sector size.=20 >=20 > What would need ot be done is to > 1. Align LUKS header (partition start) to a real sector > boundary.=20 > 2. Align the start of the filesystem area in that > partition to a real sector boundary. >=20 > Both are only possible to do realiably when you know the > sector size. All of my 3 SSDs claim 512 byte sectors, > which is almost certainly a lie. Performance is also going to suck if you don't get alignment right on drives with 4Kb sectors. FWIW here are the links I use to deal with 4Kb sector issues. http://ata.wiki.kernel.org/index.php/ATA_4_KiB_sector_issues http://lists.debian.org/debian-user/2011/01/msg02021.html Karl Free Software: "You don't pay back, you pay forward." -- Robert A. Heinlein