From owner-freebsd-fs@FreeBSD.ORG Tue Apr 29 01:08:15 2014 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 5435DF01; Tue, 29 Apr 2014 01:08:15 +0000 (UTC) Received: from esa-annu.net.uoguelph.ca (esa-annu.mail.uoguelph.ca [131.104.91.36]) by mx1.freebsd.org (Postfix) with ESMTP id E9F4E1928; Tue, 29 Apr 2014 01:08:14 +0000 (UTC) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AqIEAMr6XlODaFve/2dsb2JhbABZhCyCZb8Bgw+BMXSCJQEBBSNWGw4KAgINGQJZBohUpT+jQxeBKYxYDxU0B4JvgUoEq2qDTSGBLAEfIg X-IronPort-AV: E=Sophos;i="4.97,948,1389762000"; d="scan'208";a="118162562" Received: from muskoka.cs.uoguelph.ca (HELO zcs3.mail.uoguelph.ca) ([131.104.91.222]) by esa-annu.net.uoguelph.ca with ESMTP; 28 Apr 2014 21:08:13 -0400 Received: from zcs3.mail.uoguelph.ca (localhost.localdomain [127.0.0.1]) by zcs3.mail.uoguelph.ca (Postfix) with ESMTP id CA022B3EEF; Mon, 28 Apr 2014 21:08:13 -0400 (EDT) Date: Mon, 28 Apr 2014 21:08:13 -0400 (EDT) From: Rick Macklem To: Ivan Voras Message-ID: <969953602.3152044.1398733693818.JavaMail.root@uoguelph.ca> In-Reply-To: Subject: Re: RFC: using ceph as a backend for an NFSv4.1 pNFS server MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [172.17.91.203] X-Mailer: Zimbra 7.2.1_GA_2790 (ZimbraWebClient - FF3.0 (Win)/7.2.1_GA_2790) Cc: freebsd-fs@freebsd.org X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 29 Apr 2014 01:08:15 -0000 Ivan Voras wrote: > On 26/04/2014 21:47, Rick Macklem wrote: > > > Any other comments w.r.t. this would be appreciated, including > > generic stuff like "we couldn't care less about pNFS" or technical > > details/opinions. > > > > Thanks in advance for any feedback, rick > > ps: I'm no where near committing to do this at this point and > > I do realize that even completing the ceph port to FreeBSD > > might be beyond my limited resources. > > What functionality from ceph would pNFS really need? Would pNFS need > to > be implemented with a single back-end storage like ceph or could it > be > modular? (I don't have much experience here but it looks like HDFS is > becoming popular for some big-data applications). > > >From a quick glance, HDFS (Hadoop) uses a weak consistency model and is designed for write once, read many files. (It does not appear to be POSIX compliant.) Swift sounds somewhat similar, in that it has a "eventually consistent" rule. I'll take a closer look at it, but at first glance it doesn't sound like it would be appropriate as a back end to a pNFS server. (pNFS clients expect to see what they get from NFS, except they can do the reads/writes other ways.) Thanks everyone for the comments so far, rick rick