From mboxrd@z Thu Jan 1 00:00:00 1970 From: Loic Dachary Subject: Re: ceph-disk improvements Date: Sat, 2 Apr 2016 10:52:58 +0200 Message-ID: <56FF886A.3080406@dachary.org> References: <2041558235.2113.160e133c-ee3f-4c6e-9b8b-e4d468651d78.open-xchange@ox.pcextreme.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from relay2-d.mail.gandi.net ([217.70.183.194]:58790 "EHLO relay2-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751353AbcDBIxD (ORCPT ); Sat, 2 Apr 2016 04:53:03 -0400 In-Reply-To: <2041558235.2113.160e133c-ee3f-4c6e-9b8b-e4d468651d78.open-xchange@ox.pcextreme.nl> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Wido den Hollander , ceph-devel@vger.kernel.org Hi Wido, On 02/04/2016 07:54, Wido den Hollander wrote: >=20 >> Op 1 april 2016 om 17:36 schreef Sage Weil : >> >> >> Hi all, >> >> There are a couple of looming features for ceph-disk: >> >> 1- Support for additional devices when using BlueStore. There can b= e up=20 >> to three: the main device, a WAL/journal device (small, ~128MB, idea= lly=20 >> NVRAM), and a fast metadata device (as big as you have available; wi= ll be=20 >> used for internal metadata). >> >> 2- Support for setting up dm-cache, bcache, and/or FlashCache undern= eath=20 >> filestore or bluestore. >> >=20 > Keep in mind that you can't create a partition on a bcache device. So= when using > bcache, the journal has to be filebased and not a partition. Is this true of all bcache versions ( https://bcache.evilpiepirate.org/= ) ? Or is it a planned feature ? Or is it never going to happen ? Cheers >=20 > If we add the flag --file-based-journal or --no-partitions we can cre= ate OSDs on > both bcache and dm-cache. >=20 > With BlueStore this becomes a problem since it requires the small (XF= S) > filesystem for it's metadata. >=20 > Wido >=20 >> The current syntax of >> >> ceph-disk prepare [--dmcrypt] [--bluestore] DATADEV [JOURNALDEV] >> >> isn't terribly expressive. For example, the journal device size is = set=20 >> via a config option, not on the command line. For bluestore, the me= tadata=20 >> device will probably want/need explicit user input so they can ensur= e it's=20 >> 1/Nth of their SSD (if they have N HDDs to each SSD). >> >> And if we put dmcache in there, that partition will need to be sized= too. >> >> Another consideration is that right now we don't play nice with LVM = at=20 >> all. Should we? dm-cache is usually used in conjunction with LVM=20 >> (although it doesn't have to be). Does LVM provide value? Like, th= e=20 >> ability for users to add a second SSD to a box and migrate cache, wa= l, or=20 >> journal partitions around? >> >> I'm interested in hearing feedback on requirements, approaches, and=20 >> interfaces before we go too far down the road... >> >> Thanks! >> sage >> -- >> To unsubscribe from this list: send the line "unsubscribe ceph-devel= " in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel"= in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >=20 --=20 Lo=C3=AFc Dachary, Artisan Logiciel Libre -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html