From mboxrd@z Thu Jan 1 00:00:00 1970 From: Martin Fick Subject: Replacing DRBD use with RBD Date: Tue, 4 May 2010 16:46:12 -0700 (PDT) Message-ID: <801672.55708.qm@web36106.mail.mud.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from web36106.mail.mud.yahoo.com ([66.163.179.220]:34682 "HELO web36106.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1757309Ab0EDXqO convert rfc822-to-8bit (ORCPT ); Tue, 4 May 2010 19:46:14 -0400 Sender: ceph-devel-owner@vger.kernel.org List-ID: To: ceph-devel@vger.kernel.org Hello, I have a questions with respect to RADOS and RBD and the cluster monito= r daemons. 1) Is there any chance that the cluster monitor protocol will be enhanc= ed to work practically with only 2 monitor daemons?=A0 I ask since this= seems like it would allow a 2 node RBD based device to effectively rep= lace a DRBD based device and yet be much more easily expandable to more= nodes than DRBD.=A0 Many HA systems (say telco racks) only have two no= des and it seems silly to miss out on the opportunity to be able to use= RBD in those systems. One suggestion I have would be to do this would be to use some of the s= ame techniques that heartbeat uses to determine whether a node has gone= down or if instead there is network segregation: a serial port connect= ion, common ping nodes (such as a router)... I suspect that if reliable 2 node operation were designed into RBD, it = would eventually replace some of the uses of DRBD. 2) Is there any way of preventing two users of an RBD device from using= the device concurrently?=A0 Is there someway to create "locks" with RA= DOS that would die if a node dies?=A0 If so, this would allow an RBD de= vice to be safely mounted as a non distributed FS such as ext3 exclusiv= ely on one of many hosts.=A0 This would open up the use of RBD devices = for linux containers or linux vservers which could run on any machine i= n a cluster (similar to the idea of using it with kvm/qemu). Thanks, I look forward to playing with RBD and ceph! -Martin =20 -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html