From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nix Subject: Re: Add Bcache to an existing Filesystem Date: Tue, 27 Jun 2017 14:45:08 +0100 Message-ID: <878tkdy26z.fsf@esperi.org.uk> References: <46fc48b2-55db-471f-8318-5e60555e228e@upx.com> <864cf409-86ca-dbe1-c6bc-89667a978f44@upx.com> <20170627104654.Horde.qG1pMDnsa0LUeSdzxkMOzCc@webmail.nde.ag> <87d19py36k.fsf@esperi.org.uk> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from icebox.esperi.org.uk ([81.187.191.129]:52240 "EHLO mail.esperi.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752112AbdF0NpL (ORCPT ); Tue, 27 Jun 2017 09:45:11 -0400 In-Reply-To: (FERNANDO FREDIANI's message of "Tue, 27 Jun 2017 10:37:47 -0300") Sender: linux-bcache-owner@vger.kernel.org List-Id: linux-bcache@vger.kernel.org To: FERNANDO FREDIANI Cc: linux-bcache@vger.kernel.org On 27 Jun 2017, FERNANDO FREDIANI said: > Hello Nix > > What exactlly you mean by "exploded" ? Has it stopped working at all > and has that stopped the systems running on the top of it or it just > stopped the caching device and the backing continued to work well. It stopped the caching device and refused to mount the rootfs atop it until I explicitly dissociated it. I haven't reactivated it since (I might do so once I've rejigged my shutdown process to fully unmount everything via the early root filesystem, but this system is a crucial machine in active use and it takes ages to get around to such things). See . > Regarding my scenario, just to clarify I have 4 x /dev/sdX forming a > /dev/md124 in RAID 10. This /dev/md124 is the backing device of my > bcache which in turn has /dev/nvme0n1 as the caching device making > /dev/bcache0. I guess this would be the most coming scenario right ? I think so: s/RAID 10/journalled RAID 6/ and you have my setup (well, part of it: the start of the disk is in uncached RAID-0, and the end is in unjournalled, uncached RAID-6 with a write bitmap, but the middle portion is a RAID-6 with bcache -- albeit, presently, in 'none' mode.) -- NULL && (void)