From owner-freebsd-geom@FreeBSD.ORG Thu Dec 28 21:38:54 2006 Return-Path: X-Original-To: freebsd-geom@freebsd.org Delivered-To: freebsd-geom@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 450AE16A40F for ; Thu, 28 Dec 2006 21:38:54 +0000 (UTC) (envelope-from arne_woerner@yahoo.com) Received: from web30311.mail.mud.yahoo.com (web30311.mail.mud.yahoo.com [209.191.69.73]) by mx1.freebsd.org (Postfix) with SMTP id ECA5913C46D for ; Thu, 28 Dec 2006 21:38:53 +0000 (UTC) (envelope-from arne_woerner@yahoo.com) Received: (qmail 68160 invoked by uid 60001); 28 Dec 2006 21:38:53 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding:Message-ID; b=cfqKVktgvnu8J5dXDZAu8+xEHZ5O9yaEx9vOnNojlDNIaSMULUTOq0oLLCFLonLk13I/b3dWlh2Ukw8o8+d5RkUVz2+4K5t8ckt2/TCSSNXrycurRIOAmpmj2srfzk94hCawddDQ9AQkQMKgdSysUqlPr4G0BopFbMJFmpRblkY=; X-YMail-OSG: z2oRZgYVM1lJ.2twD_aq1SEQShvBFl5bKlgD70kfkjUtNQBTtHJVOAV6jsNpGGQArsAERGWkqp_gkCzEs1gI4kmVCa7QNpwLKrbruOwv4bf5fAYdbdIIQdymUYLKUGqD2Fuu7xdpZLCwL8pC4J0Q3S5yO.c1XJl36g-- Received: from [85.212.9.184] by web30311.mail.mud.yahoo.com via HTTP; Thu, 28 Dec 2006 13:38:52 PST Date: Thu, 28 Dec 2006 13:38:52 -0800 (PST) From: "R. B. Riddick" To: Ivan Voras , freebsd-geom@freebsd.org In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Message-ID: <332760.68142.qm@web30311.mail.mud.yahoo.com> Cc: Subject: Re: gstripe performance scaling with many disks X-BeenThere: freebsd-geom@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: GEOM-specific discussions and implementations List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 28 Dec 2006 21:38:54 -0000 I found this static intmax_t default_stripesize = 4096; in src/sbin/geom/class/stripe/geom_stripe.c The stripe-fast feature will help less and less (just as Ivan described it). A solution would be to increase stripe size to something bigger (like 64KB), so that always two drives r busy (128KB/64KB), but then u would not see speeds higher than 2 times single-drive-speed, because dd does not read ahead on a raw device (UFS would possibly). You could try your own "dd", that issues 20 read requests nearly at the same time, so that this 128KB limitations does not have an impact... Or u could try raidtest (from ports), which can already do multiple simultaneous requests (but random read and not sequential read; but ur read performance is not limited by the disk but by ipfw, IIRC)... gcache certainly would do some read-ahead, too... -Arne __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com