From owner-freebsd-questions@FreeBSD.ORG Sat Jul 16 20:33:53 2005 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 2981316A41F for ; Sat, 16 Jul 2005 20:33:53 +0000 (GMT) (envelope-from nikolas.britton@gmail.com) Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.192]) by mx1.FreeBSD.org (Postfix) with ESMTP id AA9B043D49 for ; Sat, 16 Jul 2005 20:33:52 +0000 (GMT) (envelope-from nikolas.britton@gmail.com) Received: by wproxy.gmail.com with SMTP id i11so795196wra for ; Sat, 16 Jul 2005 13:33:52 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:reply-to:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=Y2rRast4gudnGkcOP2y+QoM4IGrDSAHIh4UbUG10Ui1/6O/DtOimXgSUgP+ySv4S9zGCcwPMMHTQ/k5d5z0x7ZSVydjwZnjAmMeh4uSxdb1PYy0kx3pKoMwGgQ4C+waZPWkHUw+QFombXi3ze6WBOuBMeFhmh8x/lmnNXxWQWK8= Received: by 10.54.34.67 with SMTP id h67mr810439wrh; Sat, 16 Jul 2005 13:33:51 -0700 (PDT) Received: by 10.54.124.11 with HTTP; Sat, 16 Jul 2005 13:33:51 -0700 (PDT) Message-ID: Date: Sat, 16 Jul 2005 15:33:51 -0500 From: Nikolas Britton To: Chuck Swiger In-Reply-To: <42D9249A.2050007@mac.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline References: <42D9249A.2050007@mac.com> Cc: FreeBSD - Questions Subject: Re: RAID Level 55 X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Nikolas Britton List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 16 Jul 2005 20:33:53 -0000 On 7/16/05, Chuck Swiger wrote: > Nikolas Britton wrote: > > I was reading on wikipedia about RAIDs trying to pass the time and I > > was thinking why not have RAID 5+5 or 5+5+5 levels, sure you waste > > 2/3th's of your space but wouldn't this be a killer setup for a > > directory server where fast reads are of the utmost importance? >=20 > Actually, no. RAID-5 prioritizes cost and reliability at the expense of > performance. RAID-5 does adequate for read-mostly volumes with big files= , and > does worst with lots of writes to small files. Ok then, a public FTP server... It doesn't matter, when your have a 405,000 RPM drive (27 drives * 15k rpm) you can do just about anything, but it would excel for data reads and especially random data reads. >=20 > RAID-5,0 or -1,0 would be a much better choice. >=20 > > Would you add up the transfer rates for each drive to get the total > > transfer rate of the array?, if true you could easily saturate a 10 > > gigabit ethernet connection with a 555 array of IDE or SATA drives. >=20 > Nope. Most machines are limited by their PCI bus and chipset to less tha= n > 1Gb/s of backplace bandwidth, although the higher-end boxes with multiple= PCI > busses or PCIe will do better. Yes I realize that the PCI bus is limited to a maximum of 260MB/s (32-bit @ 66MHz) but PCI-X @ 133MHz is 1060MB/s.... Anyways... I was just thinking out loud if there would be a useful purpose for this type of RAID array, I was bored because I had to wait for ethereal to build and then I had to wait till 3am, to do something, before I could go to sleep for the night.