Date: Thu, 23 Aug 2007 08:01:27 +0400 (GST) From: Rakhesh Sasidharan <rakhesh@rakhesh.com> To: Michel Talon <talon@lpthe.jussieu.fr> Cc: freebsd-questions@freebsd.org Subject: Re: GEOM, Vinum difference Message-ID: <20070823080035.O50542@obelix.home.rakhesh.com> In-Reply-To: <20070822083729.GA93337@lpthe.jussieu.fr> References: <20070822083729.GA93337@lpthe.jussieu.fr>
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Michel Talon wrote: > Rakhesh Sasidharan wrote: > >> Another (related) question: both gvinum and the geom utilities like >> gmirror and gstripe etc provide for RAID0, RAID1, and RAID3. Any >> advantages/ disadvantages of using one instead of the other? > > There has been a polemic between Greg Lehey and PJ Dawidek about the > comparative advantages of raid3 and raid5. You can find the exchanges on > Google. One example being: > http://arkiv.freebsd.se/?ml=freebsd-performance&a=2004-08&t=227183 > As far as i remember there are arguments showing that raid3 is better > than raid5 both in terms of speed and of data security. It seems that > raid5 has mostly a hype factor for him, but i may err. Anyways it is for > such reasons that in the modern geom system, raid3 has been implemented > and not raid5. But vinum has been ported to the geom framework for the > benefit of old users, or of people who like it. For example if you are > using FreeBSD-4 or DragonFlyBSD, vinum is the standard tool, and you > may prefer getting expertise in just one tool. > > Finally none of these raid systems is really good, both for performance > and security. If you are concerned with your data and want good write > speed, you must buy enough disks and use raid 10. Another important > factor is ease of use. The geom tools, gmirror, gstripe, graid3, etc. > are *very* easy to use. The documentation in the man pages is clear, > sufficient for doing work, and not too long. On the contrary, vinum was > traditionaly documented in a very hermetic way. But more recently, Greg > Lehey has provided a very clear chapter of his book on his web site > which can be recommanded, but is not short. Note the documentation is a > critical aspect of such systems because its lack may bite you in case a > disk crashes and you need to adopt correct procedures under stress. > Also for some time the gvinum stuff was extremely buggy, and was > completely non functional when i tried it. I hope it is fixed now. Great, thanks Michael! :) That's just the sort of info I was looking for ... Regards, - Rakhesh http://rakhesh.com/
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