From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <35e14588dc09d81d03d2acb6e9cd66b2@plan9.escet.urjc.es> To: 9fans@cse.psu.edu Subject: Re: [9fans] devfs From: "Fco. J. Ballesteros" Date: Tue, 23 Nov 2004 15:01:22 +0100 In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="upas-axhhjzoobgwbikwqlisdjaesjd" Topicbox-Message-UUID: 0a43b224-eace-11e9-9e20-41e7f4b1d025 This is a multi-part message in MIME format. --upas-axhhjzoobgwbikwqlisdjaesjd Content-Disposition: inline Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In our case, we setup mirrors for different partitions in the opposite order. For example, fossil is sdC0 then sdD0, but venti is sdD0 then sdC0. This seems to be enough to keep both disks being used at the same time. Anyway, nobody here has ever tried to optimize disk usage here. --upas-axhhjzoobgwbikwqlisdjaesjd Content-Type: message/rfc822 Content-Disposition: inline Received: from mail.cse.psu.edu ([130.203.4.6]) by aquamar; Tue Nov 23 14:54:01 MET 2004 Received: from psuvax1.cse.psu.edu (localhost [127.0.0.1]) by mail.cse.psu.edu (CSE Mail Server) with ESMTP id DBEE163E0D for ; Tue, 23 Nov 2004 08:53:51 -0500 (EST) X-Original-To: 9fans@cse.psu.edu Delivered-To: 9fans@cse.psu.edu Received: from localhost (localhost [127.0.0.1]) by mail.cse.psu.edu (CSE Mail Server) with ESMTP id BCE3E63DA8 for <9fans@cse.psu.edu>; Tue, 23 Nov 2004 08:53:43 -0500 (EST) Received: from mail.cse.psu.edu ([127.0.0.1]) by localhost (psuvax1 [127.0.0.1]) (amavisd-new, port 10024) with LMTP id 11601-01-21 for <9fans@cse.psu.edu>; Tue, 23 Nov 2004 08:53:41 -0500 (EST) Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.206]) by mail.cse.psu.edu (CSE Mail Server) with ESMTP id 7C0F063DA5 for <9fans@cse.psu.edu>; Tue, 23 Nov 2004 08:53:41 -0500 (EST) Received: by wproxy.gmail.com with SMTP id 68so301356wri for <9fans@cse.psu.edu>; Tue, 23 Nov 2004 05:53:41 -0800 (PST) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:reply-to:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:references; b=bNMt7IrNOTdkaFqs7Io04OmD+9qAL8rmh6M5EE/WBUlOzmjpskVGA2n1JsLtI6MLzllPjFuW3cpk701x3nZPKFDKqnzrF+jxQoC3fzo22S7xzGyX3pFfExEWDYEyuogIK5re0na0SPzISn131Gvk8npQjeX8wExLiI84BIjNc50= Received: by 10.54.13.20 with SMTP id 20mr228750wrm; Tue, 23 Nov 2004 05:53:37 -0800 (PST) Received: by 10.54.22.57 with HTTP; Tue, 23 Nov 2004 05:53:36 -0800 (PST) Message-ID: Date: Tue, 23 Nov 2004 07:53:36 -0600 From: Eric Van Hensbergen To: Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu> Subject: Re: [9fans] devfs In-Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit References: <20041123040223.GV44345@cassie.foobarbaz.net> X-Virus-Scanned: by amavisd-new at cse.psu.edu X-BeenThere: 9fans@cse.psu.edu X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Eric Van Hensbergen , Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu> List-Id: Fans of the OS Plan 9 from Bell Labs <9fans.cse.psu.edu> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: 9fans-bounces+nemo=lsub.org@cse.psu.edu Errors-To: 9fans-bounces+nemo=lsub.org@cse.psu.edu On Mon, 22 Nov 2004 21:30:01 -0700, andrey mirtchovski wrote: > >>From reading the code, it looks like mirrors in devfs > > are read preferring the first drive in the mirror, and > > only reading from the second drive if there's a > > failure. Is this correct, and if so, is anyone working > > on round-robin reading to improve read performance? > > > > i believe that is true. > > would reading every other block from the second one improve > performance? > What does RAID-1 do? Maybe every other block isn't the right granularity, but it seems like farming out requests between the multiple drives would be the right approach. - eric --upas-axhhjzoobgwbikwqlisdjaesjd--