From owner-freebsd-geom@FreeBSD.ORG Fri Jan 20 11:30:17 2012 Return-Path: Delivered-To: freebsd-geom@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 6901510656D3; Fri, 20 Jan 2012 11:30:10 +0000 (UTC) (envelope-from mavbsd@gmail.com) Received: from mail-ee0-f54.google.com (mail-ee0-f54.google.com [74.125.83.54]) by mx1.freebsd.org (Postfix) with ESMTP id 6B3DB8FC16; Fri, 20 Jan 2012 11:30:09 +0000 (UTC) Received: by eekb47 with SMTP id b47so168602eek.13 for ; Fri, 20 Jan 2012 03:30:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=sender:message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; bh=UyA9G7fRiIQWUHDV9A5OZdRRSDSBdH1ggsxuB6+0rLE=; b=N1jqEeXVmGB/98dylboUEg83gkYEUpLTtIlvEemBAjU5nwD1Xh3+XNGmG0m+awTD2y TGsJHoXZh0oWo15OkMmXUVdaDnjvlxJodIorDADzhDmBlCOHyjgBntd8U0VkKRMFWJGH B8bAEMfX+PaheFnS8wEeqvaT/W8NhkPfZXLQU= Received: by 10.213.110.2 with SMTP id l2mr7678555ebp.22.1327059008234; Fri, 20 Jan 2012 03:30:08 -0800 (PST) Received: from mavbook2.mavhome.dp.ua (pc.mavhome.dp.ua. [212.86.226.226]) by mx.google.com with ESMTPS id n17sm10385781eei.3.2012.01.20.03.30.05 (version=SSLv3 cipher=OTHER); Fri, 20 Jan 2012 03:30:06 -0800 (PST) Sender: Alexander Motin Message-ID: <4F19503B.2090200@FreeBSD.org> Date: Fri, 20 Jan 2012 13:30:03 +0200 From: Alexander Motin User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:9.0) Gecko/20111227 Thunderbird/9.0 MIME-Version: 1.0 To: Nikolay Denev References: <4EAF00A6.5060903@FreeBSD.org> <05E0E64F-5EC4-425A-81E4-B6C35320608B@neveragain.de> <4EB05566.3060700@FreeBSD.org> <20111114210957.GA68559@in-addr.com> <059C17DB-3A7B-41AA-BF91-2F8EBAF17D01@gmail.com> <4F19474A.9020600@FreeBSD.org> <-2439788735531654851@unknownmsgid> In-Reply-To: <-2439788735531654851@unknownmsgid> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Gary Palmer , FreeBSD-Current , Dennis K?gel , "freebsd-geom@freebsd.org" Subject: Re: RFC: GEOM MULTIPATH rewrite 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: Fri, 20 Jan 2012 11:30:17 -0000 On 01/20/12 13:08, Nikolay Denev wrote: > On 20.01.2012, at 12:51, Alexander Motin wrote: > >> On 01/20/12 10:09, Nikolay Denev wrote: >>> Another thing I've observed is that active/active probably only makes sense if you are accessing single LUN. >>> In my tests where I have 24 LUNS that form 4 vdevs in a single zpool, the highest performance was achieved >>> when I split the active paths among the controllers installed in the server importing the pool. (basically "gmultipath rotate $LUN" in rc.local for half of the paths) >>> Using active/active in this situation resulted in fluctuating performance. >> >> How big was fluctuation? Between speed of one and all paths? >> >> Several active/active devices without knowledge about each other with some probability will send part of requests via the same links, while ZFS itself already does some balancing between vdevs. >> >> -- >> Alexander Motin > > I will test in a bit and post results. > > P.S.: Is there a way to enable/disable active-active on the fly? I'm > currently re-labeling to achieve that. No, there is not now. But for experiments you may achieve the same results by manually marking as failed all paths except one. It is not dangerous, as if that link fail, all other will resurrect automatically. -- Alexander Motin