From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from magic.merlins.org ([209.81.13.136]:43972 "EHLO mail1.merlins.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932194AbeGCFmS (ORCPT ); Tue, 3 Jul 2018 01:42:18 -0400 Date: Mon, 2 Jul 2018 22:42:16 -0700 From: Marc MERLIN To: Paul Jones Cc: "linux-btrfs@vger.kernel.org" Subject: Re: how to best segment a big block device in resizeable btrfs filesystems? Message-ID: <20180703054216.GJ5567@merlins.org> References: <20180701232202.vehg7amgyvz3hpxc@merlins.org> <5a603d3d-620b-6cb3-106c-9d38e3ca6d02@cn.fujitsu.com> <20180702032259.GD5567@merlins.org> <9fbd4b39-fa75-4c30-eea8-e789fd3e4dd5@cn.fujitsu.com> <20180702140527.wfbq5jenm67fvvjg@merlins.org> <3728d88c-29c1-332b-b698-31a0b3d36e2b@gmx.com> <20180702151853.mwlrinipbihq46zu@merlins.org> <20180703040650.GG5567@merlins.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 In-Reply-To: Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Tue, Jul 03, 2018 at 04:26:37AM +0000, Paul Jones wrote: > I don't have any experience with this, but since it's the internet let me tell you how I'd do it anyway 😝 That's the spirit :) > raid5 > dm-crypt > lvm (using thin provisioning + cache) > btrfs > > The cache mode on lvm requires you to set up all your volumes first, then > add caching to those volumes last. If you need to modify the volume then > you have to remove the cache, make your changes, then re-add the cache. It > sounds like a pain, but having the cache separate from the data is quite > handy. I'm ok enough with that. > Given you are running a backup server I don't think the cache would > really do much unless you enable writeback mode. If you can split up your > filesystem a bit to the point that btrfs check doesn't OOM that will > seriously help performance as well. Rsync might be feasible again. I'm a bit warry of write caching with the issues I've had. I may do write-through, but not writeback :) But caching helps indeed for my older filesystems that are still backed up via rsync because the source fs is ext4 and not btrfs. Thanks for the suggestions Marc -- "A mouse is a device used to point at the xterm you want to type in" - A.S.R. Microsoft is to operating systems .... .... what McDonalds is to gourmet cooking Home page: http://marc.merlins.org/