From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: Forever growing data in ceph using RBD image Date: Thu, 17 Jul 2014 09:47:12 -0700 Message-ID: <20140717164712.GA4690@infradead.org> References: <53C7D97D.3010607@kepler.cl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from bombadil.infradead.org ([198.137.202.9]:57916 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932908AbaGQQrM (ORCPT ); Thu, 17 Jul 2014 12:47:12 -0400 Content-Disposition: inline In-Reply-To: <53C7D97D.3010607@kepler.cl> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Alphe Salas Cc: ceph-devel On Thu, Jul 17, 2014 at 10:11:09AM -0400, Alphe Salas wrote: > Usually when I talk to dev team about this problem they tell me that the > real problem is the lack of trim in XFS, but my own analysis shows that the > real problem is ceph internal way to handle data. It is ceph that never > discard any replicas and never "clean" itself to only keep records of the > data in use. XFS supports TRIM just fine - with -o discard it will issue TRIMs on unlink, and with fstrim you can do it explicitly. Note that the online discard might be very slow for all Linux filesystems, although I've not actually tested it on top of RBD.