From owner-freebsd-fs@FreeBSD.ORG Tue Aug 28 06:20:48 2012 Return-Path: Delivered-To: freebsd-fs@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 52AC7106564A; Tue, 28 Aug 2012 06:20:48 +0000 (UTC) (envelope-from mad@madpilot.net) Received: from micro.madpilot.net (micro.madpilot.net [88.149.173.206]) by mx1.freebsd.org (Postfix) with ESMTP id E128D8FC19; Tue, 28 Aug 2012 06:20:47 +0000 (UTC) Received: from micro.madpilot.net (localhost [127.0.0.1]) by micro.madpilot.net (Postfix) with ESMTP id 3X5fwZ2gLVz28x; Tue, 28 Aug 2012 08:20:46 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=madpilot.net; h= content-transfer-encoding:content-type:content-type:in-reply-to :references:subject:subject:mime-version:user-agent:from:from :date:date:message-id:received:received; s=mail; t=1346134843; x=1347949244; bh=kR44LED0s+6tUl1OO7HmaCDybfqPyKcaLZIRMv1/iSw=; b= WwUJkyjQVeVxziVAox81KiR1Pf5XLUA62fI42oWl4EBHBijIWzmSY0frbrzqhvD+ j5ToJjuy5yulHlNQWO0IsmWzqms/1iXf4w+JB0iEkQl5D4e76ASfJr/stN3+o3cd 3Ffyoou+XgtRrTvSyR4cGnf++YWvBqlIhS+bYkt3AMU= X-Virus-Scanned: amavisd-new at madpilot.net Received: from micro.madpilot.net ([127.0.0.1]) by micro.madpilot.net (micro.madpilot.net [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Rg_NYEp0ATvs; Tue, 28 Aug 2012 08:20:43 +0200 (CEST) Received: from marvin.madpilot.net (localhost [127.0.0.1]) by micro.madpilot.net (Postfix) with ESMTP; Tue, 28 Aug 2012 08:20:43 +0200 (CEST) Message-ID: <503C633B.2070508@madpilot.net> Date: Tue, 28 Aug 2012 08:20:43 +0200 From: Guido Falsi User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:14.0) Gecko/20120727 Thunderbird/14.0 MIME-Version: 1.0 To: Matthew Seaman References: <503C5F2A.701@FreeBSD.org> In-Reply-To: <503C5F2A.701@FreeBSD.org> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-fs@FreeBSD.org Subject: Re: ZFS snapshot Folder Disappearing X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 28 Aug 2012 06:20:48 -0000 On 08/28/12 08:03, Matthew Seaman wrote: > On 28/08/2012 00:33, Tim Gustafson wrote: >>> Did you try "zfs set snapdir=visible " ? >> >> I did not, but I never set them to be invisible either, and also when I did: >> >> ls -al /tank/export/projects/www/.zfs >> >> I saw a "snapshot" folder listed there; it was only when I tried: >> >> ls -al /tank/export/projects/www/.zfs/snapshot >> >> that I got the "Not a directory" message. > > I got bitten by this. It seemed to be triggered by cvsup'ing the Ports > CVS repo -- ever since the switch to SVN it hasn't bothered me at all. > > Anyhow, to the point: I first noticed this on a zpool which was built > under 8.1 originally, and had since tracked 8-STABLE and then 9-STABLE. > I tried a bunch of things to see if I could make the problem go away, > including the nuclear option: splitting the mirror, wiping one of the > drives, building a whole new zpool on it, using send..recv to move the > data over, reboot onto the new zpool, wipe original disk then add it to > the new zpool as the other half of a mirror. > > Didn't work. Whatever the problem is, I believe it is still present in > the latest ZFS code. (Can't say for sure because like I said, I'm > simply not running the sort of IO patterns that would trigger the > problem any more.) > > There's a PR for this somewhere (not created by me), but I can't find it > in my records right now. > http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/156781 I got hit by this a few times too. Ti me it looks like it's easier to get this problem on more low spec machines(low spec regarding ZFS, so anything under 3-4 GiB ram is on the low side, for example). Using nullfs across snapshots did trigger this easily. I did that to have a nullfs mounted snapshot of the whole filesystem structure. I'm using read only zfs clones for that now. -- Guido Falsi