From owner-freebsd-questions@FreeBSD.ORG Tue Nov 20 13:00:36 2007 Return-Path: Delivered-To: questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 80E2316A41A for ; Tue, 20 Nov 2007 13:00:36 +0000 (UTC) (envelope-from joao.barros@gmail.com) Received: from nf-out-0910.google.com (nf-out-0910.google.com [64.233.182.191]) by mx1.freebsd.org (Postfix) with ESMTP id 1F76413C508 for ; Tue, 20 Nov 2007 13:00:35 +0000 (UTC) (envelope-from joao.barros@gmail.com) Received: by nf-out-0910.google.com with SMTP id b2so1747357nfb for ; Tue, 20 Nov 2007 05:00:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; bh=WOpRhxcKsrt5d9fM0XL/BxjguyoZTpJvwjk2upq1KG4=; b=t2PMR5eHNR9mpBbSpm6UPwMkp50RduwSpcMfzP97OO7rpL3kn8OMKmBUD+T+5ZbJNNPI/vCR/O9u7dt31XISSPtoe8zKMR2PoBnoKPP11jwDF3AEOfgbRI7qxxpfA7t6jJLZ535kHw1v/J0gfO0aZC0m4wRHZknL8/I2p0rAEKg= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=SThAWEYEU0rzVirxBfjVyRgAIIaKE0TWoCGHZjWxdvvVnKDUJGhJcAT6vJsZOWZCgmF2AlT4GjSSr38/xtI7cA4ocz97Cf0mRzwZ4oK67IEUHsJSIg8vbAexqbjHHEGHGsKEY5Z6RMYRjJEfHljuZqnAVCo40eFIfibAZ3UtJiU= Received: by 10.78.168.1 with SMTP id q1mr6536970hue.1195562041844; Tue, 20 Nov 2007 04:34:01 -0800 (PST) Received: by 10.78.187.19 with HTTP; Tue, 20 Nov 2007 04:34:01 -0800 (PST) Message-ID: <70e8236f0711200434y3694c11auc0bd2e92d17fa44a@mail.gmail.com> Date: Tue, 20 Nov 2007 12:34:01 +0000 From: "Joao Barros" To: "FreeBSD Questions" MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline Cc: Subject: Weird %busy in systat X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 20 Nov 2007 13:00:36 -0000 I'm doing a zpool scrub to exercise my system and noticed one strange thing when looking at the output of 'systat -vm': Disks ad0 ad1 ad4 ad6 ar0 ar1 KB/t 44.87 44.71 45.47 45.44 0.00 0.00 tps 162 163 160 162 0 0 MB/s 7.11 7.13 7.11 7.18 0.00 0.00 %busy 100 100 63 62 0 0 where: ad0: 305245MB at ata0-master SATA150 ad1: 305245MB at ata0-slave SATA150 ad4: 305245MB at ata2-master SATA150 ad6: 305245MB at ata3-master SATA150 are connected to: atapci0: port 0xb000-0xb03f,0xb400-0xb40f,0xb800-0xb87f mem 0xfc024000-0xfc024fff,0xfc000000-0xfc01ffff irq 23 at device 4.0 on pci4 atapci1: port 0x1f0-0x1f7,0x3f6,0x170-0x177,0x376,0xf000-0xf00f irq 18 at device 31.2 on pci0 and my zpool is: config: NAME STATE READ WRITE CKSUM r4x320 ONLINE 0 0 0 raidz1 ONLINE 0 0 0 ad0s1d ONLINE 0 0 0 ad1s1d ONLINE 0 0 0 ad4 ONLINE 0 0 0 ad6 ONLINE 0 0 0 Why is %busy so different when the disks are doing the same thing? The only difference is the SATA controllers and zfs using a slice on half of them and a whole disk with the other half. What is taken into account when calculating %busy? I can go read code but was hoping for someone with specific knowledge to answer :) -- Joao Barros