From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (ext-mx10.extmail.prod.ext.phx2.redhat.com [10.5.110.39]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u3Q7EuPp020560 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Tue, 26 Apr 2016 03:14:56 -0400 Received: from mr001msb.fastweb.it (mr001msb.fastweb.it [85.18.95.85]) by mx1.redhat.com (Postfix) with ESMTP id CF17162645 for ; Tue, 26 Apr 2016 07:14:54 +0000 (UTC) Received: from ceres.assyoma.it (93.63.55.57) by mr001msb.fastweb.it (8.5.140.04) id 571739DD004B47B4 for linux-lvm@redhat.com; Tue, 26 Apr 2016 09:12:04 +0200 Received: from gdanti-laptop.assyoma.it (unknown [172.31.255.5]) (using TLSv1.2 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ceres.assyoma.it (Postfix) with ESMTPSA id 33D56267226 for ; Tue, 26 Apr 2016 09:12:02 +0200 (CEST) References: <5714EE58.8080400@assyoma.it> <571A2F6C.6050006@redhat.com> <571B350F.9050708@assyoma.it> <571DE943.40204@redhat.com> From: Gionatan Danti Message-ID: <571F14B9.8020706@assyoma.it> Date: Tue, 26 Apr 2016 09:11:53 +0200 MIME-Version: 1.0 In-Reply-To: <571DE943.40204@redhat.com> Content-Transfer-Encoding: 7bit Subject: Re: [linux-lvm] Testing ThinLVM metadata exhaustion Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: LVM general discussion and development > bugzilla.redhat.com > > Anyway - 6.8 will likely be your solution. > > Thin-provisioning is NOT supposed to be used at 'corner' cases - we > improve them, but older version simply had more of them as there was > always clearly communicated do not over-provision if you can't provide > the space. > > Out-of-space is not equal if you run out of your filesystem space - you > can't expect things will continue to work nicely - the cooperation of > block layer with filesystem and metadata resilience are continually > improved. > > We have actually even seen users 'targeting' to hit full-pool as a part > of regular work-flow - bad bad plan... > > Regards > > Zdenek [reposting due to sender error] Hi Zdenek, thanks for your courtesy. I absolutely agree with you that in no case metadata exhaustion can be considered part of a "regular work-flow". At the same time, I often do "stress test" specifically crafted to put the software/hardware in the worst possible condition. In this manner, should an exceptionally bad situation occour, I know how to deal with it. I have another question: does this bug only happen when metadata space is exausted? I am asking this because searching for other peoples with the same error message, I read this bug report: http://www.redhat.com/archives/dm-devel/2014-March/msg00021.html The bug described in the message above does not necessarily happen at metadata exaustion time, as confirmed here: https://bugzilla.kernel.org/show_bug.cgi?id=68801 I understand that these are old (2014) bugs and that were fixed in Linux 3.14 but, using thin LVM volumes in production systems (albeit with RH 7 only), I want to be reasonably sure that no show-stopper bug can hit me. Are current RH OSes (6.7 and 7.2) immune from this bug (metadata corruption even if tmeta is not full)? Thanks. -- Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti@assyoma.it - info@assyoma.it GPG public key ID: FF5F32A8