From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40156) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YJdnx-0007sy-7v for qemu-devel@nongnu.org; Fri, 06 Feb 2015 02:58:22 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YJdnt-0006ee-7f for qemu-devel@nongnu.org; Fri, 06 Feb 2015 02:58:21 -0500 Received: from tama50.ecl.ntt.co.jp ([129.60.39.147]:46644) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YJdns-0006dj-O6 for qemu-devel@nongnu.org; Fri, 06 Feb 2015 02:58:17 -0500 Message-ID: <54D47403.5070507@lab.ntt.co.jp> Date: Fri, 06 Feb 2015 16:57:55 +0900 From: Teruaki Ishizaki MIME-Version: 1.0 References: <1422347727-13006-1-git-send-email-ishizaki.teruaki@lab.ntt.co.jp> <20150202065226.GB9217@ubuntu-trusty> <54D1A5FB.5060709@lab.ntt.co.jp> <20150206021100.GA19864@ubuntu-trusty> In-Reply-To: <20150206021100.GA19864@ubuntu-trusty> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v4] sheepdog: selectable object size support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Liu Yuan Cc: kwolf@redhat.com, mitake.hitoshi@lab.ntt.co.jp, sheepdog@lists.wpkg.org, qemu-devel@nongnu.org, stefanha@redhat.com (2015/02/06 11:18), Liu Yuan wrote: > On Wed, Feb 04, 2015 at 01:54:19PM +0900, Teruaki Ishizaki wrote: >> (2015/02/02 15:52), Liu Yuan wrote: >>> On Tue, Jan 27, 2015 at 05:35:27PM +0900, Teruaki Ishizaki wrote: >>>> Previously, qemu block driver of sheepdog used hard-coded VDI object size. >>>> This patch enables users to handle "block_size_shift" value for >>>> calculating VDI object size. >>>> >>>> When you start qemu, you don't need to specify additional command option. >>>> >>>> But when you create the VDI which doesn't have default object size >>>> with qemu-img command, you specify block_size_shift option. >>>> >>>> If you want to create a VDI of 8MB(1 << 23) object size, >>>> you need to specify following command option. >>>> >>>> # qemu-img create -o block_size_shift=23 sheepdog:test1 100M >>> >>> Is it possible to make this option more user friendly? such as >>> >>> $ qemu-img create -o object_size=8M sheepdog:test 1G >> >> At first, I thought that the object_size was user friendly. >> But, Sheepdog has already the value of block_size_shift >> in the inode layout that means like object_size. >> >> 'object_size' doesn't always fit right in 'block_size_shift'. >> On the other hands, 'block_size_shift' always fit right in >> 'object_size'. >> >> I think that existing layout shouldn't be changed easily and >> it seems that it is difficult for users to specify >> the object_size value that fit right in 'block_size_shift'. > > I don't think we need to change the layout. block_size_shift is what QEMU talks > to sheep, and QEMU options is what users talks to QEMU. We can convert the user > friendly object size into block_size_shift internally in the driver before > sending it tosheep daemon, no? > For example, users specify 12MB for object size, block_size_shift doesn't fit exactly to an integer. I suppose that normally an administrator do format sheepdog cluster with specifying block_size_shift and users usually do qemu-img command without a block_size_shift option. I think that the block_size_shift option of qemu-img command is used for a experimental purpose. Thanks, Teruaki Ishizaki