From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christopher James Halse Rogers Subject: Re: How to create bcachefs? Date: Thu, 25 Aug 2016 10:03:07 +1000 Message-ID: <1472083387.31787.0@mail.cooperteam.net> References: <20160824065212.fzs2nk3rg7z7iudb@kmo-pixel> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Return-path: Received: from mail.cooperteam.net ([150.101.105.211]:58062 "EHLO mail.cooperteam.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757086AbcHYGi3 (ORCPT ); Thu, 25 Aug 2016 02:38:29 -0400 In-Reply-To: Sender: linux-bcache-owner@vger.kernel.org List-Id: linux-bcache@vger.kernel.org To: marcin@mejor.pl Cc: linux-bcache@vger.kernel.org On Thu, Aug 25, 2016 at 7:21 AM, marcin@mejor.pl wrote: > W dniu 24.08.2016 o 08:52, Kent Overstreet pisze: > [...] > > Hi! >> Hey, sorry for the long delay, been sick past several days. > > I was afraid that I'm asking to easy question:) And I hope everything > is > fine with you now! > > >> The way arguments >> were passed to bcache format was a holdover from old style >> make-bcache, and >> didn't make much sense for bcachefs - -C was used for all devices, >> and --tier >> specifies fast devices and slow devices. >> >> I finally got around to redoing the option parsing so we don't need >> the -C >> argument today - update your bcache tools, and the command you want >> is now: >> >> bcache format --tier 0 /dev/sde1 --tier 1 /dev/sdd1 >> >> (assuming sde1 is your fast device and sdd1 is your slow device). > > Does it means that cache is unavailable and only tiering will be in > bcachefs? > And... How to mount tiered FS? When I pass one device in mount I'm > getting: > bcache: bch_open_as_blockdevs() register_cache_set err insufficient > devices Tiering gets you all the advantages of caching, plus you can (with some effort) have the combined filesystem size be the sum of the SSD + HDD capacities, rather than the capacity be determined solely by the capacity of the slow tier (this is not currently the case for bcachefs). To mount a tiered FS you can either pass all the relevant devices to mount, like: mount -t bcache /dev/sda:/dev/sdb:/dev/sdc /mountpoint (I haven't tested this recently) or ensure that all the relevant devices have been registered with bcache, like so: echo /dev/sda | sudo tee /sys/fs/bcache/register_quiet echo /dev/sdb | sudo tee /sys/fs/bcache/register_quiet echo /dev/sdc | sudo tee /sys/fs/bcache/register_quiet mount -t bcache /dev/sdb /mountpoint (you can use any member of the set as the device to mount in this case).