From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adam Nielsen Subject: Newbie questions Date: Mon, 01 Oct 2012 22:30:43 +1000 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from plane.gmane.org ([80.91.229.3]:46760 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750929Ab2JAMfH (ORCPT ); Mon, 1 Oct 2012 08:35:07 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1TIfDE-0008WC-6S for ceph-devel@vger.kernel.org; Mon, 01 Oct 2012 14:35:04 +0200 Received: from 124-170-67-40.dyn.iinet.net.au ([124.170.67.40]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 01 Oct 2012 14:35:04 +0200 Received: from a.nielsen by 124-170-67-40.dyn.iinet.net.au with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 01 Oct 2012 14:35:04 +0200 Sender: ceph-devel-owner@vger.kernel.org List-ID: To: ceph-devel@vger.kernel.org Hi all, I've been investigating cluster filesystems for a while now, and I have a few questions about Ceph I hope you don't mind me asking here. This is in the context of using Ceph as a POSIX filesystem and alternative to something like NFS. 1. Is Ceph stable enough for "real" use yet? I read that upgrading to v0.48 required a reformat, which I imagine would be a bit of an issue in a production system. Is this how upgrades are normally done? Is anyone running Ceph in a production environment with real data yet? 2. Why does the wiki say that you can run one or three monitor daemons, but running two is worse than one? Wouldn't running two be less work than running three? 3. If I have multiple disks in a machine that I can dedicate to Ceph, is it better to RAID them and present Ceph with a single filesystem, or do you get better results by giving Ceph a filesystem on each disk and letting it look after the striping and any faulty disks? 4. How resilient is the system? I can find a lot of information saying one node can go away without any data loss, but does that mean losing a second node will take everything down? Can you configure it such that every node has a complete copy of the cluster, so as long as any one node survives, all the data is available? 5. Given that the cluster filesystem contains files, which are then stored as other files in a different filesystem, does this affect performance much? I'm thinking of something like a git repository which accesses file metadata a lot, and seems to suffer a bit if it's not running off a local disk. Hopefully I'm not asking questions which are already covered in the documentation - if so please point me in the right direction. Many thanks, Adam.