From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent CARON Subject: Re: RAID 5 of RAID 5's? Date: Mon, 13 Jun 2005 09:15:39 +0200 Message-ID: <42AD329B.4080103@apartia.fr> References: <1118187572.15459.96.camel@seki.nac.uci.edu> <42A93D30.6080900@apartia.fr> <1118436219.25226.252.camel@seki.nac.uci.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1118436219.25226.252.camel@seki.nac.uci.edu> Sender: linux-raid-owner@vger.kernel.org To: Dan Stromberg Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Dan Stromberg a =E9crit : >On Fri, 2005-06-10 at 09:11 +0200, Laurent CARON wrote: > =20 > >>Dan Stromberg a =E9crit : >> >> =20 >> >>>Has anyone constructed a RAID 5 of RAID 5's using mdadm on a linux >>>system? >>> >>>Was it reliable? >>> >>>How large was it? >>> >>>Thanks! >>> >>>=20 >>> >>> =20 >>> >>Seems to be a large waste of space.... >> =20 >> > >Consider: > >You have a bunch of "bricks" that can shuffle data between a NAS head >and a bunch of disks. > >The disks are RAID'd (through the "bricks"), but if one of the bricks >themselves dies, you're kinda stuck. > >But if you RAID 5 the RAID 5's, then you don't end up with massive >parity pounding, and your bricks aren't a single point of failure, and >you don't lose as much space as if you mirrored. > >Sound copacetic? > >Thanks for your feedback! > > =20 > RAID 10 is IMHO a bit more efficient. Raid 5 means at least 9 disks: Usable capacity: 4 Disks Read speed: Good Write speed: poor Raid 10 with 8 disks can store the same amount of data. Read speed: Average Write Speed: Better than raid5 - To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html