From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Elsayed Subject: Re: Replacing DRBD use with RBD Date: Wed, 05 May 2010 00:30:39 -0700 Message-ID: References: <801672.55708.qm@web36106.mail.mud.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7Bit Return-path: Received: from lo.gmane.org ([80.91.229.12]:49178 "EHLO lo.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752880Ab0EEHZE (ORCPT ); Wed, 5 May 2010 03:25:04 -0400 Received: from list by lo.gmane.org with local (Exim 4.69) (envelope-from ) id 1O9Yyd-0006AZ-16 for ceph-devel@vger.kernel.org; Wed, 05 May 2010 09:25:03 +0200 Received: from rain.gmane.org ([80.91.229.7]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 05 May 2010 09:25:03 +0200 Received: from eternaleye by rain.gmane.org with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 05 May 2010 09:25:03 +0200 Sender: ceph-devel-owner@vger.kernel.org List-ID: To: ceph-devel@vger.kernel.org Martin Fick wrote: > Hello, > > I have a questions with respect to RADOS and RBD and the cluster monitor > daemons. I'm not one of the developers, but I've been following for a while and one of your sub-questions intriqued me; specifically: >...This would open up the use of RBD devices for linux > containers or linux vservers which could run on any machine in a cluster > (similar to the idea of using it with kvm/qemu). As it currently stands you could likely run a vserver or an OpenVZ/Virtuozzo/LXC container on Ceph (the distributed FS) directly, rather than layering a local FS over RBD. Also, this would probably provide better performance in the end. As a side benefit, you would gain the ability to make fine-grained snapshots of the guests' filesystems, access them directly from the host (or another Ceph client), and adjust quotas for the guest while running. This is probably a better solution for container-based virtualization than RBD-based options, due to the advantage one can take of all guests sharing a kernel with the host. RBD is more likely to be useful for full virtualization like KVM, but even in that case you could probably make a specialized initramfs that mounts a rootfs over Ceph with a prefix (taking advantage of that Ceph allows mounting a subdirectory as if it was the whole FS). Hope this helps!