From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from frost.carfax.org.uk ([85.119.82.111]:56747 "EHLO frost.carfax.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161027AbeBOTL5 (ORCPT ); Thu, 15 Feb 2018 14:11:57 -0500 Date: Thu, 15 Feb 2018 19:11:55 +0000 From: Hugo Mills To: "Ellis H. Wilson III" Cc: Btrfs BTRFS Subject: Re: Metadata / Data on Heterogeneous Media Message-ID: <20180215191155.GP3807@carfax.org.uk> References: <1b2df382-0402-a806-9ebf-996fabf22ba4@panasas.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="Eclf2LUqbhpvYoNt" In-Reply-To: <1b2df382-0402-a806-9ebf-996fabf22ba4@panasas.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: --Eclf2LUqbhpvYoNt Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Feb 15, 2018 at 12:15:49PM -0500, Ellis H. Wilson III wrote: > In discussing the performance of various metadata operations over > the past few days I've had this idea in the back of my head, and > wanted to see if anybody had already thought about it before > (likely, I would guess). > > It appears based on this page: > https://btrfs.wiki.kernel.org/index.php/Btrfs_design > that data and metadata in BTRFS are fairly well isolated from one > another, particularly in the case of large files. This appears > reinforced by a recent comment from Qu ("...btrfs strictly > split metadata and data usage..."). > > Yet, while there are plenty of options to RAID0/1/10/etc across > generally homogeneous media types, there doesn't appear to be any > functionality (at least that I can find) to segment different BTRFS > internals to different types of devices. E.G., place metadata trees > and extent block groups on SSD, and data trees and extent block > groups on HDD(s). > > Is this something that has already been considered (and if so, > implemented, which would make me extremely happy)? Is it feasible > it is hasn't been approached yet? I admit my internal knowledge of > BTRFS is fleeting, though I'm trying to work on that daily at this > time, so forgive me if this is unapproachable for obvious > architectural reasons. Well, it's been discussed, and I wrote up a theoretical framework which should cover a wide range of use-cases: https://www.spinics.net/lists/linux-btrfs/msg33916.html I never got round to implementing it, though -- I ran into issues over storing the properties/metadata needed to configure it. Hugo. -- Hugo Mills | Dullest spy film ever: The Eastbourne Ultimatum hugo@... carfax.org.uk | http://carfax.org.uk/ | PGP: E2AB1DE4 | The Thick of It --Eclf2LUqbhpvYoNt Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJahdt7AAoJEFheFHXiqx3kWPkQALNrXFU8ehBlbZvtx+Ktbn5O Oq9iq+Iopn0ssDm6yH5aF+nsHPMU8nY6NGxgJrjG+YNpbXq5icn3HXJwgzIFfHMN ivdhdqV2carP7dcjhJRXjfX78UElRUwZN+zUFY8vj4xvJ1di25QHVWhOke8Tq3aJ LWczEXPdyJ4kSbrCNbLov+q24x2WB7dZjyFgJT6SxFwDj3M97DNJ0SOAMSLaGe56 HL+9rmqwgcxD5MAWVLnfdK+w5S5198VBpkavUlR1BgVO3QJJv8pgZYhd6piGyCpS 4BQXzRI8A1JcDHHSyyQmsEIF0Z4fp0zA8OainsTEo6KTxlhfMJtrGOE0InlBflzr dt/NnnHL5cWY93W+8zHrnirOG8zB6l3u1Zu/ScGhVWEhGvvberOrlnbJJ+w5bSQV +29mSUX1rBX6Chnj6SJlAFEFrGqlXdKGEZN70C59/ApLBxne8sRTLSRRbGyxvpMt /Na0/DHmynJXUYy6qVbUC7QdPI2vY3254Xi2MHdzxkpT7LctZl6fQemGGHOG42ZT gBEpy3cO9MOdTdnz8XAXylM0wSZn2YopmSS8xtcatPaM8iu7xO7jqm7+vAlLE8aE tHfUTm7KFWHh+2/nfNXbDvQlImtbPfF6vuuSAxriKWE6xi0W7WwsKMOdc5zMA45U 7D9xbNeDmBsTJxIDjKEf =IaB8 -----END PGP SIGNATURE----- --Eclf2LUqbhpvYoNt--