From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: TIER: combine SSDs and HDDs into a single block device Date: Fri, 3 Aug 2012 03:22:17 -0400 Message-ID: <20120803072217.GA23837@infradead.org> References: <501AB2B4.2010406@inktank.com> <20120802175700.GA16693@infradead.org> <501AF5D7.9060004@inktank.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:41814 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751167Ab2HCHWT (ORCPT ); Fri, 3 Aug 2012 03:22:19 -0400 Content-Disposition: inline In-Reply-To: <501AF5D7.9060004@inktank.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Mark Nelson Cc: Christoph Hellwig , Tommi Virtanen , ceph-devel@vger.kernel.org On Thu, Aug 02, 2012 at 04:49:11PM -0500, Mark Nelson wrote: > 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?) It's generally a bit dated and bit rotting, and as Dave said doesn't parallelize. But for a setup where you have one OSD per disk and lots of OSD that's not really quite as important.