From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Nelson Subject: Re: TIER: combine SSDs and HDDs into a single block device Date: Thu, 02 Aug 2012 16:49:11 -0500 Message-ID: <501AF5D7.9060004@inktank.com> References: <501AB2B4.2010406@inktank.com> <20120802175700.GA16693@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-ob0-f174.google.com ([209.85.214.174]:34700 "EHLO mail-ob0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753090Ab2HBVt0 (ORCPT ); Thu, 2 Aug 2012 17:49:26 -0400 Received: by obbuo13 with SMTP id uo13so24384obb.19 for ; Thu, 02 Aug 2012 14:49:25 -0700 (PDT) In-Reply-To: <20120802175700.GA16693@infradead.org> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Christoph Hellwig Cc: Tommi Virtanen , ceph-devel@vger.kernel.org On 08/02/2012 12:57 PM, Christoph Hellwig wrote: > On Thu, Aug 02, 2012 at 12:02:44PM -0500, Mark Nelson wrote: >> Alex is also trying to bug the XFS guys (and Sage bugged the BTRFS >> guys) about ways to put metadata on SSD while keeping data on >> spinning disk. It sounds like there is a hack for XFS that would let >> us keep inodes in the lower portion of a volume up to some >> configurable boundary and then we could use lvm to assign that >> portion of the volume to an SSD. The BTRFS guys have a SOC project >> in the works to separate out metadata onto another disk. > > Also with XFS you can use the realtime device for data and the main > device for all metadata. > I was thinking of doing that. Is the realtime allocator a good fit for this kind of thing? I think dchinner mentioned on the xfs mailing list last year that it's single threaded and not very well optimized (and maybe not production viable?) Mark -- Mark Nelson Performance Engineer Inktank