From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nikolaus Rath Subject: Re: bcache and LVM Date: Tue, 09 Feb 2016 08:02:01 -0800 Message-ID: <87si11euti.fsf@vostro.rath.org> References: <87k2mgo2rz.fsf@vostro.rath.org> <20160208144419.Horde.Ci1_2KcBCEnOa-WxsDN90oU@www3.nde.ag> <87r3gmrhbn.fsf@thinkpad.rath.org> <20160209114452.Horde.0AlUHBhWkB7dDF8j0jmv3SL@www3.nde.ag> 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]:32768 "EHLO out5-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754781AbcBIQCH convert rfc822-to-8bit (ORCPT ); Tue, 9 Feb 2016 11:02:07 -0500 Received: from compute6.internal (compute6.nyi.internal [10.202.2.46]) by mailout.nyi.internal (Postfix) with ESMTP id 87AEB20B6B for ; Tue, 9 Feb 2016 11:02:06 -0500 (EST) Received: from ebox.rath.org (ebox.rath.org [45.79.69.51]) by mail.messagingengine.com (Postfix) with ESMTPA id 70DB4C00020 for ; Tue, 9 Feb 2016 11:02:04 -0500 (EST) Received: from vostro.rath.org (vostro [192.168.12.4]) by ebox.rath.org (Postfix) with ESMTPS id 2FDCD1CE40E for ; Tue, 9 Feb 2016 16:02:02 +0000 (UTC) In-Reply-To: <20160209114452.Horde.0AlUHBhWkB7dDF8j0jmv3SL@www3.nde.ag> (Jens-U. Mozdzen's message of "Tue, 09 Feb 2016 11:44:52 +0100") Sender: linux-bcache-owner@vger.kernel.org List-Id: linux-bcache@vger.kernel.org To: linux-bcache@vger.kernel.org On Feb 09 2016, "Jens-U. Mozdzen" wrote: > Hi Nikolaus, > > Zitat von Nikolaus Rath : >> On Feb 08 2016, "Jens-U. Mozdzen" wrote: >>> [...] >>> The article itself does positively mention sub-dividing bcache devi= ces >>> using LVM. >> >> Yep, but the talk page then says: >> >> | Initially, LVM did not recognize my /dev/bcache0 when I wanted to >> | create a physical volume on it. For anyone else who has that issue= , >> | this may be relevant: >> | http://www.redhat.com/archives/linux-lvm/2012-March/msg00005.html. > > this still holds true even with LVM on OpenSUSE Leap 42.1 (which is > what we're using ATM) - but that's no "stability issue", but rather a= n > installation nuisance. You only need to tell LVM to consider bcache > devices at all, by extending /etc/lvm/lvm.conf. Indeed. But it's also yet another slightly worrying tidbit (maybe LVM i= s not considering it by default for a good reason). Also, just now someone on -btrfs advised: | > Otherwise I'll give bcache a shot. I've avoided it so far because o= f the | > need to reformat and because of rumours that it doesn't work well w= ith | > LVM or BTRFS. But it sounds as if that's not the case.. | | It should work fine with _just_ BTRFS, but don't put any other layers | into the storage system like LVM or dmcrypt or mdraid, it's got some | pretty pathological interactions with the device mapper and md | frameworks still. 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