From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Braid Subject: chunk size must be power of two? Date: Wed, 06 Dec 2006 21:29:06 +0000 Message-ID: <45773622.8020704@loreland.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Is there any reason the chunk size has to be a power of two? We're trying to use md devices to stripe over hardware RAID5 arrays, so to align the I/O correctly, I want to set the chunk size to (n - 1) * stripe_size for the underlying array. Which is impossible to do because mdadm (and the kernel) insist on the chunk size being a power of two. I haven't tried just removing the kernel checks yet ... is there a reason why md is limited to power of two chunk sizes? Failing that, does anyone know of anything else I can use to stripe block devices together which doesn't have the power of two limitation? device-mapper/LVM seems to have the same problem...