From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Tomas Subject: linear writes to raid5 Date: Sat, 08 Apr 2006 04:17:35 +0400 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org Cc: alex@clusterfs.com List-Id: linux-raid.ids Good day all, is there a way to batch explicitely write requests raid5 issues? for example, there is a raid5 built from 3 disks with chunk=64K. one types dd if=/dev/zero of=/dev/md0 bs=128k count=1 and 128K bio gets into the raid5. raid5 processes the request, does xor for parity stripe, then issues 2 64KB requests down to lower level. is it even possible to implement? if so, how complex? I suppose we could introduce a context which holds last non-issued bio and instead of generic_make_request() in handle_stripe() try to merge current request to the previous one from the context? how does this sound to you? thanks, Alex