From owner-freebsd-questions@freebsd.org Mon Jun 29 02:29:34 2015 Return-Path: Delivered-To: freebsd-questions@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 B616F98CCF1 for ; Mon, 29 Jun 2015 02:29:34 +0000 (UTC) (envelope-from quartz@sneakertech.com) Received: from douhisi.pair.com (douhisi.pair.com [209.68.5.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 950611B09 for ; Mon, 29 Jun 2015 02:29:34 +0000 (UTC) (envelope-from quartz@sneakertech.com) Received: from [10.2.2.1] (pool-173-48-121-235.bstnma.fios.verizon.net [173.48.121.235]) by douhisi.pair.com (Postfix) with ESMTPSA id 5726C3F6D2; Sun, 28 Jun 2015 22:29:33 -0400 (EDT) Message-ID: <5590AD8C.7030904@sneakertech.com> Date: Sun, 28 Jun 2015 22:29:32 -0400 From: Quartz User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:10.0.2) Gecko/20120216 Thunderbird/10.0.2 MIME-Version: 1.0 To: Chris Stankevitz CC: freebsd-questions Subject: Re: Corrupt GPT on ZFS full-disks that shouldn't be using GPT References: <558F99B6.2080205@sneakertech.com> <559070CC.8040105@sneakertech.com> <20150628232208.GA69625@neutralgood.org> In-Reply-To: <20150628232208.GA69625@neutralgood.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 29 Jun 2015 02:29:34 -0000 > When making changes like dd'ing the end of a disk be sure to do a scrub > after touching _only_ _one_ disk. I suggest doing scrubs until you get a > clean one. Then move on to the next disk, doing the write/scrub steps on > each disk in turn. This is good advice. > It may just make recovery more complicated. If it was me I'd just zero the > last block without the offline/online dance. ... but I'm not sure that is. >Can I use dd on a /dev/daX that is currently part of an > imported, mounted, and online zpool? There's nothing technically stopping you, but screwing with it "live" is not a great idea. At the least, if zfs IS using those blocks or otherwise notices, it will consider the drive to be throwing errors and mark it as failing, so you'll have to deal with the issue anyway. Honestly though, this whole thread is really better suited for freebsd-fs rather than freebsd-questions. You'll probably get better answers there. >Also, if anyone can answer this > question more generally, I'd appreciate it: are there times (other > than r-x) when I do not have permission/ability to dd if=/dev/zero > of=/dev/daX? It can happen. I've bumped into that once when a dvd was improperly cloned onto a usb drive and it got stuck in a weird read-only mode and I had to jump through a couple hoops to erase it (this wasn't freebsd though).