From owner-freebsd-current@FreeBSD.ORG Fri Nov 18 17:36:01 2005 Return-Path: X-Original-To: freebsd-current@freebsd.org Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 9AC4516A41F for ; Fri, 18 Nov 2005 17:36:01 +0000 (GMT) (envelope-from dan@dan.emsphone.com) Received: from dan.emsphone.com (dan.emsphone.com [199.67.51.101]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2B89343D45 for ; Fri, 18 Nov 2005 17:36:00 +0000 (GMT) (envelope-from dan@dan.emsphone.com) Received: (from dan@localhost) by dan.emsphone.com (8.13.1/8.13.3) id jAIHa0iT029580; Fri, 18 Nov 2005 11:36:00 -0600 (CST) (envelope-from dan) Date: Fri, 18 Nov 2005 11:36:00 -0600 From: Dan Nelson To: Brian Candler Message-ID: <20051118173559.GJ62141@dan.emsphone.com> References: <20051118114308.GA11281@uk.tiscali.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20051118114308.GA11281@uk.tiscali.com> X-OS: FreeBSD 5.4-STABLE X-message-flag: Outlook Error User-Agent: Mutt/1.5.11 Cc: freebsd-current@freebsd.org Subject: Re: Logical volume management X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 18 Nov 2005 17:36:01 -0000 In the last episode (Nov 18), Brian Candler said: > Vinum's manpage makes my head spin. I was wondering if anyone had > considered implementing something a bit more straightforward and also > more dynamic. > > Suppose you: > > (1) Divide all your disks up-front into equal sized chunks, say 4MB. > > (2) Use an indirection table to map each volume into an arbitary set of > these chunks across all available disks. > > (3) Store the indirection table at the end of a partition, as other > GEOM modules do for their metadata, and cache it in RAM. > > (e.g. a 160GB drive, divided into 4MB blocks, each of which has a > 32-bit indirection table entry, would require only 160KB of > indirection table) AIX does something similar in its volume manager. A volume group consists of a number of disks, split into equal-sized partitions (256MB is the default I think). Logical volumes reside in the volume group, and are composed of multiple partitions. Each LV can have its own raid/mirror characteristics separate from others, and can be grown, mirrored, or otherwise modified online. http://publib.boulder.ibm.com/infocenter/pseries/topic/com.ibm.aix.doc/aixbman/admnconc/logical_vol.htm http://publib.boulder.ibm.com/infocenter/pseries/topic/com.ibm.aix.doc/aixbman/prftungd/diskperf.htm -- Dan Nelson dnelson@allantgroup.com