From owner-svn-src-head@freebsd.org Thu May 19 14:52:46 2016 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 89B44B42B7A; Thu, 19 May 2016 14:52:46 +0000 (UTC) (envelope-from ken@kdm.org) Received: from mithlond.kdm.org (mithlond.kdm.org [96.89.93.250]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "A1-33714", Issuer "A1-33714" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 53FD710B9; Thu, 19 May 2016 14:52:46 +0000 (UTC) (envelope-from ken@kdm.org) Received: from mithlond.kdm.org (localhost [127.0.0.1]) by mithlond.kdm.org (8.15.2/8.14.9) with ESMTPS id u4JEoXct069382 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Thu, 19 May 2016 10:50:33 -0400 (EDT) (envelope-from ken@mithlond.kdm.org) Received: (from ken@localhost) by mithlond.kdm.org (8.15.2/8.14.9/Submit) id u4JEoXGl069381; Thu, 19 May 2016 10:50:33 -0400 (EDT) (envelope-from ken) Date: Thu, 19 May 2016 10:50:33 -0400 From: "Kenneth D. Merry" To: Bruce Simpson Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r300207 - in head: sbin/camcontrol sys/cam/ata sys/cam/scsi sys/dev/ahci sys/geom sys/geom/eli sys/kern sys/sys usr.sbin usr.sbin/diskinfo usr.sbin/zonectl Message-ID: <20160519145033.GA69089@mithlond.kdm.org> References: <201605191408.u4JE8aPL079390@repo.freebsd.org> <573DCE0D.70400@fastmail.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <573DCE0D.70400@fastmail.net> User-Agent: Mutt/1.5.23 (2014-03-12) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.4.3 (mithlond.kdm.org [127.0.0.1]); Thu, 19 May 2016 10:50:33 -0400 (EDT) X-Spam-Status: No, score=-2.9 required=5.0 tests=ALL_TRUSTED,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS autolearn=ham autolearn_force=no version=3.4.1 X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on mithlond.kdm.org X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 19 May 2016 14:52:46 -0000 On Thu, May 19, 2016 at 15:30:37 +0100, Bruce Simpson wrote: > Right On Commander! > > Now here is hoping the random-write issues with OpenZFS are solved... Well, this is of course only the underlying infrastructure for SMR drives. As for the random write issues with ZFS (or rather sequential I/O going out in random order), we (Spectra) are working on that in general. The original plan was to do full SMR support for ZFS, but it looks like we may get good enough write performance with Drive Managed drives by just making writes from ZFS to drives more sequential rather than going for full Host Aware and Host Managed support. If that turns out that performance isn't good enough after all, then we'll have to put in the effort to put Host Aware support at least into ZFS. That's why I said (in the commit message) that I don't know of anyone working on using the SMR infrastructure for UFS or ZFS. Now that the plumbing is in place in CAM and GEOM, it is possible at the filesystem level if someone wants to do the work. Ken -- Kenneth Merry ken@FreeBSD.ORG