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 XYjuG80Bhk82 for ; Fri, 23 Nov 2012 07:07:04 +0100 (CET) Received: from v4.tansi.org (ns.km33513-03.keymachine.de [87.118.94.3]) by mail.saout.de (Postfix) with ESMTP for ; Fri, 23 Nov 2012 07:07:04 +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 35B9D206733 for ; Fri, 23 Nov 2012 07:07:04 +0100 (CET) Date: Fri, 23 Nov 2012 07:07:20 +0100 From: Arno Wagner Message-ID: <20121123060720.GA5520@tansi.org> References: <50AEF7B3.4000807@babioch.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <50AEF7B3.4000807@babioch.de> Subject: Re: [dm-crypt] Reconsidering default options for cryptsetup-reencrypt List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: dm-crypt@saout.de On Fri, Nov 23, 2012 at 05:12:35AM +0100, Karol Babioch wrote: > Hi, > > I'm currently reencrypting my (hardware) RAID setup, which is quite big > (12 TB) in order to change the cipher from aes-xts-plain to aes-xts-plain64. > > While playing around with various options, I found out that a block size > of 64 MB and the use of direct I/O results in the highest speed for me. This seems to be RAID options (i.e. out-of-scope for cryptsetup), and very specific ones as you have some hardware RAID solution. Also 64MB block size is very, very large and will be a problem for some workloads. Also, your sped gain of 10% is negligible, as it is likely not robust and very much dependent on the workload. [...] > Maybe I'm just generalizing too much here when trying > to come up with some conclusions based on my hardware. I think you do. I also think that HW raid is a bit exotic on Linux these days, as SW RAID gives better features and often better performance. Arno -- 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