From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nikolaus Rath Subject: Re: bcache and LVM Date: Tue, 09 Feb 2016 20:09:29 -0800 Message-ID: <87mvr9tddy.fsf@vostro.rath.org> References: <87k2mgo2rz.fsf@vostro.rath.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from out5-smtp.messagingengine.com ([66.111.4.29]:55334 "EHLO out5-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755658AbcBJEJa convert rfc822-to-8bit (ORCPT ); Tue, 9 Feb 2016 23:09:30 -0500 Received: from compute5.internal (compute5.nyi.internal [10.202.2.45]) by mailout.nyi.internal (Postfix) with ESMTP id 7E83221A38 for ; Tue, 9 Feb 2016 23:09:30 -0500 (EST) Received: from ebox.rath.org (ebox.rath.org [45.79.69.51]) by mail.messagingengine.com (Postfix) with ESMTPA id 33BD26801B6 for ; Tue, 9 Feb 2016 23:09:30 -0500 (EST) Received: from vostro.rath.org (vostro [192.168.12.4]) by ebox.rath.org (Postfix) with ESMTPS id 482E31CF582 for ; Wed, 10 Feb 2016 04:09:29 +0000 (UTC) In-Reply-To: <87k2mgo2rz.fsf@vostro.rath.org> (Nikolaus Rath's message of "Sun, 07 Feb 2016 09:20:48 -0800") Sender: linux-bcache-owner@vger.kernel.org List-Id: linux-bcache@vger.kernel.org To: linux-bcache@vger.kernel.org On Feb 07 2016, Nikolaus Rath wrote: > Hello, > > The internet claims that using bcache with LVM is not a good idea > (eg. on https://wiki.archlinux.org/index.php/Bcache )- but I wasn't a= ble > to find any substantial information other than this general > recommendation. > > Is this still (or has ever been) correct? If so, what issues can aris= e? > And does this happen only when using bcache on top of an LVM LV, or a= lso > when using a bcache device as an LVM PV? I now have the following stack: btrfs on LUKS on LVM on bcache The VG contains two bcache PVs with backing devices on different spinning disks, and a shared cache device on SSD. I'm using Kernel 4.3. I'm super happy with the performance, boot times increased from 1:30 minutes to X11 and 2:00 to Firefox to roughly 0:10 to X11 and 0:30 to =46irefox. Time will tell if it also keeps my data intact, but I hope btrfs would at least detect any corruption.=20 Best, -Nikolaus (No Cc on replies please, I'm reading the list) --=20 GPG encrypted emails preferred. Key id: 0xD113FCAC3C4E599F =46ingerprint: ED31 791B 2C5C 1613 AF38 8B8A D113 FCAC 3C4E 599F =C2=BBTime flies like an arrow, fruit flies like a Banana.= =C2=AB