From mboxrd@z Thu Jan 1 00:00:00 1970 From: "John Stoffel" Subject: Re: [PATCH] md: forbid a RAID5 from having both a bitmap and a journal. Date: Wed, 18 Oct 2017 10:48:36 -0400 Message-ID: <23015.27076.469924.191613@quad.stoffel.home> References: <87bmldnjtq.fsf@notabene.neil.brown.name> <20171012173019.c2bbfyz3hgudjbhz@kernel.org> <87wp3zlj9q.fsf@notabene.neil.brown.name> <20171013195122.mi7gr4xxm77odx7t@kernel.org> <608CE47A-1C46-4087-B7D3-6FA5936C1DAF@fb.com> <877evulrpm.fsf@notabene.neil.brown.name> <20171016235609.mmo3vbqiekr4li5c@kernel.org> <87sheijw2u.fsf@notabene.neil.brown.name> <23014.27372.306872.143938@quad.stoffel.home> <8760bdjxl0.fsf@notabene.neil.brown.name> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <8760bdjxl0.fsf@notabene.neil.brown.name> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown Cc: John Stoffel , Shaohua Li , Song Liu , linux-raid , "kumba@gentoo.org" , Shaohua Li List-Id: linux-raid.ids >>>>> "NeilBrown" == NeilBrown writes: NeilBrown> On Tue, Oct 17 2017, John Stoffel wrote: >>>>>>> "NeilBrown" == NeilBrown writes: >> NeilBrown> Having both a bitmap and a journal is pointless. NeilBrown> Attempting to do so can corrupt the bitmap if the journal NeilBrown> replay happens before the bitmap is initialized. NeilBrown> Rather than try to avoid this corruption, simply NeilBrown> refuse to allow arrays with both a bitmap and a journal. NeilBrown> So: NeilBrown> - if raid5_run sees both are present, fail. >> >> So what happens if there's someone out there with an array setup with >> both already? Should the journal or the bitmap be removed at this >> time? NeilBrown> If someone has an array like that they can assemble it with NeilBrown> --update=no-bitmap NeilBrown> I'd rather not automatically disable things. That works for me, assuming there's a useful message in the logs explaining what's gone wrong here. Either mdadm emits the message, or the kernel does.