From owner-freebsd-stable@freebsd.org Mon May 20 12:53:07 2019 Return-Path: Delivered-To: freebsd-stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 4D21515AC8F8 for ; Mon, 20 May 2019 12:53:07 +0000 (UTC) (envelope-from paul@gromit.dlib.vt.edu) Received: from gromit.dlib.vt.edu (gromit.dlib.vt.edu [128.173.49.70]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "gromit.dlib.vt.edu", Issuer "Chumby Certificate Authority" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id E68477504B for ; Mon, 20 May 2019 12:53:05 +0000 (UTC) (envelope-from paul@gromit.dlib.vt.edu) Received: from mather.gromit23.net (c-98-244-101-97.hsd1.va.comcast.net [98.244.101.97]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by gromit.dlib.vt.edu (Postfix) with ESMTPSA id 4DA954BD; Mon, 20 May 2019 08:53:04 -0400 (EDT) Content-Type: text/plain; charset=us-ascii; delsp=yes; format=flowed Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.11\)) Subject: Re: trying to expand a zvol-backed bhyve guest which is UFS From: Paul Mather In-Reply-To: <20190520090907.GA36068@rpi3.zyxst.net> Date: Mon, 20 May 2019 08:53:03 -0400 Cc: freebsd-stable@freebsd.org Content-Transfer-Encoding: 7bit Message-Id: <3D467299-377E-49D1-9771-030590F72D3D@gromit.dlib.vt.edu> References: <20190520014645.GC6971@rpi3.zyxst.net> <54BFD570-E9B9-49A5-8785-2D80D4FC05D1@gromit.dlib.vt.edu> <20190520024517.GA23482@rpi3.zyxst.net> <20190520090907.GA36068@rpi3.zyxst.net> To: tech-lists X-Mailer: Apple Mail (2.3445.104.11) X-Rspamd-Queue-Id: E68477504B X-Spamd-Bar: --- Authentication-Results: mx1.freebsd.org; dmarc=fail reason="" header.from=vt.edu (policy=none) X-Spamd-Result: default: False [-3.00 / 15.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; NEURAL_HAM_MEDIUM(-1.00)[-0.999,0]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; MV_CASE(0.50)[]; IP_SCORE(-0.81)[ip: (-2.04), ipnet: 128.173.0.0/16(-1.02), asn: 1312(-0.91), country: US(-0.06)]; MIME_GOOD(-0.10)[text/plain]; DMARC_POLICY_SOFTFAIL(0.10)[vt.edu : No valid SPF, No valid DKIM,none]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; TO_MATCH_ENVRCPT_SOME(0.00)[]; MX_GOOD(-0.01)[cached: chumby.dlib.vt.edu]; RCPT_COUNT_TWO(0.00)[2]; NEURAL_HAM_SHORT(-0.69)[-0.688,0]; R_SPF_NA(0.00)[]; RECEIVED_SPAMHAUS_PBL(0.00)[97.101.244.98.zen.spamhaus.org : 127.0.0.10]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:1312, ipnet:128.173.0.0/16, country:US]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_TLS_ALL(0.00)[]; FROM_EQ_ENVFROM(0.00)[] X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 20 May 2019 12:53:07 -0000 On May 20, 2019, at 5:09 AM, tech-lists wrote: > On Sun, May 19, 2019 at 10:17:35PM -0500, Adam wrote: >> On Sun, May 19, 2019 at 9:47 PM tech-lists wrote: >> >>> Thanks very much to you both, all sorted now. I didn't realise there was >>> a 2TB limit for MBR either. Can I shrink the 4TB to 2TB on the zfs side >>> without scrambling the ufs on the guest? >> >> You can snapshot the zvol to be safe, but you should be able to shrink it >> to the existing partition size. If it's a sparse zvol, it may not may >> that >> much difference. > > The zvol has about 515GB data. Hopefully zfs is smart enough to shrink > to the MBR boundary. A ZVOL is just a container. ZFS has no implicit knowledge of what you are using it for or whether it has any particular partition table inside it. It's your responsibility to size the ZVOL appropriately. (TL;DR: ZVOLs have no concept of an "MBR boundary.") Cheers, Paul.