From user-return-12829-apmail-cassandra-user-archive=cassandra.apache.org@cassandra.apache.org Thu Feb 03 08:22:05 2011 Return-Path: Delivered-To: apmail-cassandra-user-archive@www.apache.org Received: (qmail 12108 invoked from network); 3 Feb 2011 08:22:04 -0000 Received: from hermes.apache.org (HELO mail.apache.org) (140.211.11.3) by minotaur.apache.org with SMTP; 3 Feb 2011 08:22:04 -0000 Received: (qmail 91353 invoked by uid 500); 3 Feb 2011 08:22:03 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 91248 invoked by uid 500); 3 Feb 2011 08:22:00 -0000 Mailing-List: contact user-help@cassandra.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@cassandra.apache.org Delivered-To: mailing list user@cassandra.apache.org Received: (qmail 91240 invoked by uid 99); 3 Feb 2011 08:21:59 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 03 Feb 2011 08:21:59 +0000 X-ASF-Spam-Status: No, hits=-0.0 required=5.0 tests=RCVD_IN_DNSWL_LOW,SPF_NEUTRAL X-Spam-Check-By: apache.org Received-SPF: neutral (athena.apache.org: local policy) Received: from [209.85.213.44] (HELO mail-yw0-f44.google.com) (209.85.213.44) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 03 Feb 2011 08:21:51 +0000 Received: by ywk9 with SMTP id 9so411888ywk.31 for ; Thu, 03 Feb 2011 00:21:30 -0800 (PST) MIME-Version: 1.0 Received: by 10.151.150.4 with SMTP id c4mr2723738ybo.169.1296721290377; Thu, 03 Feb 2011 00:21:30 -0800 (PST) Sender: scode@scode.org Received: by 10.151.79.21 with HTTP; Thu, 3 Feb 2011 00:21:30 -0800 (PST) X-Originating-IP: [90.234.64.164] In-Reply-To: <018e01cbc364$28c86a00$7a593e00$@com> References: <018e01cbc364$28c86a00$7a593e00$@com> Date: Thu, 3 Feb 2011 09:21:30 +0100 X-Google-Sender-Auth: 8AlYv1ofA1h_5AOXJFWw5Hra1YQ Message-ID: Subject: Re: Tracking down read latency From: Peter Schuller To: user@cassandra.apache.org Content-Type: text/plain; charset=UTF-8 > $ iostat As rcoli already mentioned you don't seen to have an I/O problem, but as a point of general recommendation: When determining whether you are blocking on disk I/O, pretty much *always* use "iostat -x" rather than the much less useful default mode of iostat. The %util and queue wait/average time columns are massively useful/important; without them one is much more blind as to whether or not storage devices are actually saturated. -- / Peter Schuller