From owner-freebsd-emulation@FreeBSD.ORG Wed Aug 13 14:25:25 2014 Return-Path: Delivered-To: vbox@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 21A1A4A5 for ; Wed, 13 Aug 2014 14:25:25 +0000 (UTC) Received: from mail-pd0-x22d.google.com (mail-pd0-x22d.google.com [IPv6:2607:f8b0:400e:c02::22d]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id EEB6D2DFA for ; Wed, 13 Aug 2014 14:25:24 +0000 (UTC) Received: by mail-pd0-f173.google.com with SMTP id w10so14534205pde.18 for ; Wed, 13 Aug 2014 07:25:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=jWgSALwWfQKnw0udqjzK4lvYamAqnjNQyG6eDQmtelA=; b=koW1AAHnXRgh6mcFSQhe6zaiSqsxCoZHJRPJCJZqowjCh5yGOmut7a3v1qD5/74vrv V6sC1p6VMaqNpRuPz8vx77hjpOgldL/n016EGoyw6xUQx3Kx3XoWdUSHmy2hgF3M3FQm bH7G0ktABP5rQ/of6X1XxknEahYI3y4ayDeVvFU1A5RvT43351DOBtPIT18z3/FpMBI5 yp+fHqnRrqtdau+wM3cO3bzfCEm2eOyyTFZxBNhcp7/Ka3+qsR56WE2UKyi/dyLwqiuk bXQNZXFHphEVRn4DLPD8m+QSyhB7TarwSZI+hejOP5MsyQWV6QxBm/aS+6CdLVv68Q46 +nOg== MIME-Version: 1.0 X-Received: by 10.66.230.163 with SMTP id sz3mr4381321pac.136.1407939924609; Wed, 13 Aug 2014 07:25:24 -0700 (PDT) Received: by 10.70.118.132 with HTTP; Wed, 13 Aug 2014 07:25:24 -0700 (PDT) In-Reply-To: <53EB570F.2000902@b1t.name> References: <53EB570F.2000902@b1t.name> Date: Wed, 13 Aug 2014 09:25:24 -0500 Message-ID: Subject: Re: ZFS zvol support improved - VirtualBox gets unstable with it From: Adam Vande More To: Volodymyr Kostyrko X-Mailman-Approved-At: Wed, 13 Aug 2014 17:04:56 +0000 Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.18-1 Cc: vbox@freebsd.org X-BeenThere: freebsd-emulation@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Development of Emulators of other operating systems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 13 Aug 2014 14:25:25 -0000 On Wed, Aug 13, 2014 at 7:16 AM, Volodymyr Kostyrko wrote: > Hi all. > > There was a long time ago when I started to use pure zvol's as VirtualBox > disks. This way virtual machines were working faster due to default smaller > cluster size and I also can snapshot them and mount right from the OS. Too > bad this also required setting 'use host i/o cache' at storage controller > properties. Without that most guest OS would just break or hang. I've been using ZVOL's as Vbox disks for maybe @ 3 years including some exported as ISCSI. The break/hang you describe is totally unfamiliar to me even though my guests include various Linux distros, different versions/types of BSD, and several flavors of Windows. These included a mixture of i386/amd64 guests. I do not set "use host i/o cache" on any systems(not all have ZVOL snapshots but most do). > > Recently 10-STABLE was shown some improvements: > > 1. zfs set volmode=dev > > Now you can mark zvol as a dev node preventing system from touching it. > Also this makes working with zvol simpler. > > 2. r269429 (MFC r269123): Implement separate I/O dispatch method for ZVOLs > in "dev" mode. > > After this one if you have zvol's marked as volmode=dev you can turn off > useHostIOCache for your virtual machines. And they would also work much > faster! But alas after that VirtualBox becomes unstable and your machines > can also fail on heavy IO. > 1 & 2 look very interesting. If that makes it into 10.1, I'll be giving it a whirl. -- Adam