From owner-freebsd-questions@FreeBSD.ORG Wed Aug 6 06:23:44 2014 Return-Path: Delivered-To: freebsd-questions@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 E9177998 for ; Wed, 6 Aug 2014 06:23:44 +0000 (UTC) Received: from sdf.lonestar.org (mx.sdf.org [192.94.73.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "mx.sdf.org", Issuer "SDF.ORG" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id C91F226B3 for ; Wed, 6 Aug 2014 06:23:44 +0000 (UTC) Received: from sdf.org (IDENT:bennett@sdf.lonestar.org [192.94.73.15]) by sdf.lonestar.org (8.14.8/8.14.5) with ESMTP id s766NZIf006855 (using TLSv1/SSLv3 with cipher DHE-RSA-AES256-GCM-SHA384 (256 bits) verified NO); Wed, 6 Aug 2014 06:23:36 GMT Received: (from bennett@localhost) by sdf.org (8.14.8/8.12.8/Submit) id s766NZ64028954; Wed, 6 Aug 2014 01:23:35 -0500 (CDT) From: Scott Bennett Message-Id: <201408060623.s766NZ64028954@sdf.org> Date: Wed, 06 Aug 2014 01:23:35 -0500 To: Daniel Staal Subject: Re: gvinum raid5 vs. ZFS raidz User-Agent: Heirloom mailx 12.4 7/29/08 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: freebsd-questions@freebsd.org X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 06 Aug 2014 06:23:45 -0000 On Sat, 02 Aug 2014 18:33:38 -0400 Daniel Staal wrote: >--As of August 2, 2014 1:21:54 AM -0500, Scott Bennett is alleged to have >said: > >>>> Does not support migration to any other Does not support migration >>>> RAID levels or their equivalents. between raidz levels, even by >>> >>> Correct. Once you have created a vdev, that vdev must remain the same >>> type. You can add mirrors to a mirror vdev, but you cannot add drives or >>> change raid level to raidz1, raidz2, or raidz3 vdevs. >> >> Too bad. Increasing the raidz level ought to be not much more >> difficult than growing the raidz device by adding more spindles. Doing >> the latter ought to be no more difficult that doing it with gvinum's >> stripe or raid5 devices. Perhaps the ZFS developers will eventually >> implement these capabilities. (A side thought: gstripe and graid3 >> devices ought also to be expandable in this manner, although the resulting >> number of graid3 components would still need to be 2^n + 1.) > >--As for the rest, it is mine. > >There actually is a semi-simple way, even if it's not direct... > >You can 'send' a ZFS filesystem to a backup drive, and then 'receive' it >back to a new pool. It will keep all file and volume level options when >you do that, but the pools can be set up differently. It's not something >you can do in-place, but it's not hard either. Right, and that's why it is actually *not* a way. A "grow" operation, as implemented in gvinum(8), is done in place. > >(Basically, it's a simplified 'backup and restore to new setup', but it is >majorly simplified.) > That would mean having/buying enough more space to be able to do that. Further, one would probably want to set up a new raidzN on those devices to hold all that output, so that one would not risk corrupting/losing one's data during the process. And if one is going to do that, then why copy it back? Growing it in place would eliminate that space requirement, perhaps saving the owner a considerable amount of money. The only additional spindles needed would be the new ones to increase the space or raidz level. Scott Bennett, Comm. ASMELG, CFIAG ********************************************************************** * Internet: bennett at sdf.org *xor* bennett at freeshell.org * *--------------------------------------------------------------------* * "A well regulated and disciplined militia, is at all times a good * * objection to the introduction of that bane of all free governments * * -- a standing army." * * -- Gov. John Hancock, New York Journal, 28 January 1790 * **********************************************************************