From owner-freebsd-stable@freebsd.org Thu Sep 22 11:56:57 2016 Return-Path: Delivered-To: freebsd-stable@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 A1262BE417F for ; Thu, 22 Sep 2016 11:56:57 +0000 (UTC) (envelope-from emz@norma.perm.ru) Received: from elf.hq.norma.perm.ru (mail.norma.perm.ru [IPv6:2a00:7540:1::5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "mail.norma.perm.ru", Issuer "Vivat-Trade UNIX Root CA" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 24C51143E for ; Thu, 22 Sep 2016 11:56:56 +0000 (UTC) (envelope-from emz@norma.perm.ru) Received: from bsdrookie.norma.com. ([IPv6:fd00::7fe]) by elf.hq.norma.perm.ru (8.15.2/8.15.2) with ESMTPS id u8MBura9036784 (version=TLSv1.2 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO) for ; Thu, 22 Sep 2016 16:56:54 +0500 (YEKT) (envelope-from emz@norma.perm.ru) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=norma.perm.ru; s=key; t=1474545414; bh=aNqY3RqpJv4OYOPqCxUv7SDzZNfcRs+Smwqu8Mbe9PA=; h=From:Subject:To:Date; b=Aa75zAqMA5VhctbhYf6qhKvxotB03KHumngXnVwTYjfDBApuwtZGUpDIjTVnXFqZJ Xj9yz0KE5ejGi7UniV+JHiMnUeDEu5Df2xIZsgomW3Zxr7TlW+JftiY6SiOfb4EJ4P ZxmV+Rdu3y4dhXzrVWVTNdMIA3AEd1eEL5KJCwrk= From: "Eugene M. Zheganin" Subject: zvol clone diffs To: freebsd-stable@FreeBSD.org Message-ID: <57E3C705.2010702@norma.perm.ru> Date: Thu, 22 Sep 2016 16:56:53 +0500 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:38.0) Gecko/20100101 Thunderbird/38.7.0 MIME-Version: 1.0 Content-Type: text/plain; charset=koi8-r Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 22 Sep 2016 11:56:57 -0000 Hi. I should mention from the start that this is a question about an engineering task, not a question about FreeBSD issue. I have a set of zvol clones that I redistribute over iSCSI. Several Windows VMs use these clones as disks via their embedded iSCSI initiators (each clone represents a disk with an NTFS partition, is imported as a "foreign" disk and functions just fine). From my opinion, they should not have any need to do additional writes on these clones (each VM should only read data, from my point of view). But zfs shows they do, and sometimes they write a lot of data, so clearly facts and expactations differ a lot - obviously I didn't take something into accounting. Is there any way to figure out what these writes are ? Because I cannot propose any simple enough method. Thanks. Eugene.