From owner-freebsd-current@FreeBSD.ORG Tue Dec 20 10:07:13 2011 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E03531065673 for ; Tue, 20 Dec 2011 10:07:13 +0000 (UTC) (envelope-from se@freebsd.org) Received: from nm18.bullet.mail.bf1.yahoo.com (nm18.bullet.mail.bf1.yahoo.com [98.139.212.177]) by mx1.freebsd.org (Postfix) with SMTP id 691898FC22 for ; Tue, 20 Dec 2011 10:07:13 +0000 (UTC) Received: from [98.139.212.148] by nm18.bullet.mail.bf1.yahoo.com with NNFMP; 20 Dec 2011 10:07:12 -0000 Received: from [98.139.211.160] by tm5.bullet.mail.bf1.yahoo.com with NNFMP; 20 Dec 2011 10:07:12 -0000 Received: from [127.0.0.1] by smtp217.mail.bf1.yahoo.com with NNFMP; 20 Dec 2011 10:07:12 -0000 X-Yahoo-Newman-Id: 622425.95073.bm@smtp217.mail.bf1.yahoo.com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: Nm.s6asVM1n2rD75Qct_2AMBeiPHN2ANIpV0SUzV6awPdav xql8.NTCAB836kbqGaT4ScB5WmiFiksChF.MNbQhVrhJ_YLyxSvtcq8LSVBa DOXPWmz2gqYZ357pg7qQd.J5XTU7plwAHfJnAbgjDhcnjA_Qko99U3v75kGH ChvvI7kuUyai5MjWTdmWqflxUD.85ppyllEqrWzA5gpre8.J7jqmF1hoQgZT 2XVzRHp6l7pu.66ZCniT8LpHSybzGXSB_5uixKIl47XydYZX8MkIqM9kn5d4 ghl6j2qD7lM96ChWR21X6FcrYjaNzQZZ2uYQTkwPgfBIcS.cIkR_4dFG7O.B fF_kknJsGcGJhJH91F.2uWCDDR8p7ZHnzX1VB.Od5URP_ZHU1AilwmtmqCl9 5MoWRi4X.LV2IY9mw X-Yahoo-SMTP: iDf2N9.swBDAhYEh7VHfpgq0lnq. Received: from [192.168.119.20] (se@81.173.153.254 with plain) by smtp217.mail.bf1.yahoo.com with SMTP; 20 Dec 2011 02:07:12 -0800 PST Message-ID: <4EF05E4C.5090702@freebsd.org> Date: Tue, 20 Dec 2011 11:07:08 +0100 From: Stefan Esser User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:8.0) Gecko/20111105 Thunderbird/8.0 MIME-Version: 1.0 To: Michael Reifenberger References: <4EEF488E.1030904@freebsd.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: FreeBSD Current Subject: Re: Uneven load on drives in ZFS RAIDZ1 X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 20 Dec 2011 10:07:14 -0000 Am 19.12.2011 17:36, schrieb Michael Reifenberger: > Hi, > a quick test using `dd if=/dev/zero of=/test ...` shows: > > dT: 10.004s w: 10.000s filter: ^a?da?.$ > L(q) ops/s r/s kBps ms/r w/s kBps ms/w %busy Name > 0 378 0 0 12.5 376 36414 11.9 60.6| ada0 > 0 380 0 0 12.2 378 36501 11.8 60.0| ada1 > 0 382 0 0 7.7 380 36847 11.6 59.2| ada2 > 0 375 0 0 7.4 374 36164 9.6 51.3| ada3 > 0 377 0 1 10.2 375 36325 10.1 53.3| ada4 > 10 391 0 0 39.3 389 38064 15.7 80.2| ada5 > > Seems to be sufficiently equally distributed for a life system... Hi Michael, in an earlier reply I mentioned the suspicious queue length and %busy of ada5, which may be the result of other load (not caused by the dd command) or of a hardware problem (I'd check drive health ...). (Hmmm, the numbers look strange: ops/s is not the sum of r/s and w/s, but misses that value by 2. I could understand a rounding difference of 1, but not 2 counts per second. But this is a different issue ...) Anyway: The imbalance that I observe on my system is specific to reads, not writes. Could you please check, whether sending a large (multi-GB) file to /dev/null shows identical read load over all drives? I suspect that 2 of the drives will see slightly (some 20%, perhaps) less read requests than the rest. Regards, STefan