From owner-freebsd-fs Wed Apr 3 8:51:46 2002 Delivered-To: freebsd-fs@freebsd.org Received: from quic.net (romulus.quic.net [216.23.27.8]) by hub.freebsd.org (Postfix) with SMTP id 6DFF937B41B for ; Wed, 3 Apr 2002 08:51:42 -0800 (PST) Received: (qmail 15730 invoked by uid 1032); 3 Apr 2002 16:51:49 -0000 From: utsl@quic.net Date: Wed, 3 Apr 2002 11:51:49 -0500 To: freebsd-fs@freebsd.org Subject: Re: LVM support Message-ID: <20020403165149.GA15377@quic.net> References: <20020402063328.77704.qmail@web8103.in.yahoo.com> <20020402063504.GA9042@hollin.btc.adaptec.com> <20020403101751.A39874@wantadilla.lemis.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20020403101751.A39874@wantadilla.lemis.com> User-Agent: Mutt/1.3.27i Sender: owner-freebsd-fs@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org On Wed, Apr 03, 2002 at 10:17:51AM +0930, Greg 'groggy' Lehey wrote: > I know a number of people involved in the Linux storage systems area. > With one exception, they all *hate* LVM. A number have looked at > Vinum and would have liked to have it on Linux. I don't see any > advantage in porting the Linux LVM to FreeBSD. > > Note also that LVM only has some of the functionality of Vinum. In > particular, you'd need the md or raid drivers as well. The Linux LVM is awful. But of course, it's design was copied from HP-UX, and its LVM feels like it was designed by a commitee. I've been looking at switching to EVMS, because its reimplementation of LVM seems to fix couple of the more irritating bugs. (I'm unable to move those systems to FreeBSD yet. :-() I only know of one thing LVM has working (not as well as EVMS+devfs) that Vinum doesn't seem to: root filesystem support. There are benefits and disadvantages to having separate software raid. I used to work with Veritas a lot, and frequently had to configure large systems with striped and mirrored volumes. These were database volumes, and I'd typically see requests for something like 30 volumes of 2G each striped across six disks, and mirrored across another 6. It could have been a lot easier, if I could have configured the stripes and mirrors once, and created volumes all the same. On the other hand, the LVM setup is a lot less flexible, and if a mirror breaks, it's hard to tell which volumes are affected. Another important differance is that Vinum and Veritas seem to give the sysadmin more control over disk layout. LVM makes that difficult, and for the most part tries to hide it. In my experience, volume layout can make a vast difference in performance. ---Nathan To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message