From mboxrd@z Thu Jan 1 00:00:00 1970 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Date: Mon, 25 Apr 2016 18:52:52 +0200 From: Gionatan Danti In-Reply-To: <571DE943.40204@redhat.com> References: <5714EE58.8080400@assyoma.it> <571A2F6C.6050006@redhat.com> <571B350F.9050708@assyoma.it> <571DE943.40204@redhat.com> Message-ID: 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 Cc: Zdenek Kabelac > > 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 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