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 ISM8-USicmes for ; Wed, 16 Jan 2013 12:23:23 +0100 (CET) Received: from v4.tansi.org (ns.km33513-03.keymachine.de [87.118.94.3]) by mail.saout.de (Postfix) with ESMTP for ; Wed, 16 Jan 2013 12:23:22 +0100 (CET) Received: from gatewagner.dyndns.org (84-74-164-49.dclient.hispeed.ch [84.74.164.49]) by v4.tansi.org (Postfix) with ESMTPA id D987220681A for ; Wed, 16 Jan 2013 12:23:21 +0100 (CET) Date: Wed, 16 Jan 2013 12:23:21 +0100 From: Arno Wagner Message-ID: <20130116112321.GA6637@tansi.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [dm-crypt] Memory errors and and 3TB RAID5 partition List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: dm-crypt@saout.de Hi Frederico, impossible to quantify, and you may also get errors in the busses, controller and (very rare unless overclocked) CPU. The thing about "massive file corruption" is a myth though: Most flipped bit just lead to a flipped bit because they happen before encryption. Even after encryption, you lose only one 512 byte sector per flipped bit. What you do is, if this is critical, _underclock_ everything in your machine by 10-20%, get ECC RAM, ensure good cooling and clean power. Before undercklocking, test the machine extensively at 100% speed or maybe even 110% or the like. An alternative is to verify each write. Here you have to be careful to empty all buffers and caches before doing it. That is what I do for large files. Arno On Wed, Jan 16, 2013 at 12:08:15PM +0100, Federico Foschini wrote: > Hi all, > I'm reading the FAQ on cryptsetup wiki because I'm plannig to set up a > software raid 5 (mdadm) with 3 1,5TB disks and I'm a bit scared about > memory errors. I read that a single flipped bit can lead in a massive > file corruption and I've got 2GB of non ECC ram on my machine... what > is the risk of encounter a memory error writing big files (like 8-10 > GiB)? > > -- > Federico Foschini. > _______________________________________________ > dm-crypt mailing list > dm-crypt@saout.de > http://www.saout.de/mailman/listinfo/dm-crypt -- Arno Wagner, Dr. sc. techn., Dipl. Inform., Email: arno@wagner.name GnuPG: ID: CB5D9718 FP: 12D6 C03B 1B30 33BB 13CF B774 E35C 5FA1 CB5D 9718 ---- One of the painful things about our time is that those who feel certainty are stupid, and those with any imagination and understanding are filled with doubt and indecision. -- Bertrand Russell