Return-Path: Delivered-To: apmail-incubator-cassandra-user-archive@minotaur.apache.org Received: (qmail 30026 invoked from network); 4 Dec 2009 20:10:25 -0000 Received: from hermes.apache.org (HELO mail.apache.org) (140.211.11.3) by minotaur.apache.org with SMTP; 4 Dec 2009 20:10:25 -0000 Received: (qmail 60555 invoked by uid 500); 4 Dec 2009 20:10:25 -0000 Delivered-To: apmail-incubator-cassandra-user-archive@incubator.apache.org Received: (qmail 60529 invoked by uid 500); 4 Dec 2009 20:10:25 -0000 Mailing-List: contact cassandra-user-help@incubator.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: cassandra-user@incubator.apache.org Delivered-To: mailing list cassandra-user@incubator.apache.org Received: (qmail 60520 invoked by uid 99); 4 Dec 2009 20:10:25 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 04 Dec 2009 20:10:25 +0000 X-ASF-Spam-Status: No, hits=-2.6 required=5.0 tests=AWL,BAYES_00 X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: domain of jbellis@gmail.com designates 209.85.219.220 as permitted sender) Received: from [209.85.219.220] (HELO mail-ew0-f220.google.com) (209.85.219.220) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 04 Dec 2009 20:10:22 +0000 Received: by ewy20 with SMTP id 20so1108095ewy.0 for ; Fri, 04 Dec 2009 12:09:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :from:date:message-id:subject:to:content-type :content-transfer-encoding; bh=4eEIPIdjkFpwu1ZemFigLZmXE7v53CAaH6dllSP8uyg=; b=UNxWGtNfIto+UTQS7GfI79AU/8v+uilmL66oUcnNqk4L2X3bp2TUrypLF93CQkusWR noF2f76clz7k+6dFBoCfk/wHGepiypIJdRP3zKlmsWZ2IRQ4jrw+uaKbL/7sYuvfCmm0 cOMUdhJfvzHqoX1EBYkT0LfY5jnJKHnofMqgA= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :content-type:content-transfer-encoding; b=Oi4FPWmUbvaO91IXoGfbHFHU89TQwlHXrFIniX9c2s1XjFP9UdcQm9leg+kuOo4pge 7yjFD9JKf5MM0S4p0subbtqIi1tqtjEYlkw8eaSTKaBsbabzF0dQl5c8kiP1mmpDjajF 6oUtvSPF03MDZUHRbKXWmwEpitaNsn6Iwn/c4= MIME-Version: 1.0 Received: by 10.216.90.85 with SMTP id d63mr1219961wef.14.1259957398182; Fri, 04 Dec 2009 12:09:58 -0800 (PST) In-Reply-To: <59DD1BA8FD3C0F4C90771C18F2B5B53A4C85126687@GVW0432EXB.americas.hpqcorp.net> References: <59DD1BA8FD3C0F4C90771C18F2B5B53A4C850190C6@GVW0432EXB.americas.hpqcorp.net> <59DD1BA8FD3C0F4C90771C18F2B5B53A4C850C22D8@GVW0432EXB.americas.hpqcorp.net> <59DD1BA8FD3C0F4C90771C18F2B5B53A4C850C2317@GVW0432EXB.americas.hpqcorp.net> <59DD1BA8FD3C0F4C90771C18F2B5B53A4C85126629@GVW0432EXB.americas.hpqcorp.net> <1259953660.2898.96.camel@btoddb-laptop> <59DD1BA8FD3C0F4C90771C18F2B5B53A4C85126687@GVW0432EXB.americas.hpqcorp.net> From: Jonathan Ellis Date: Fri, 4 Dec 2009 14:09:38 -0600 Message-ID: Subject: Re: Persistently increasing read latency To: cassandra-user@incubator.apache.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On Fri, Dec 4, 2009 at 1:31 PM, Freeman, Tim wrote: >>Fundamentally there's only so much I/O you can do at a time. =A0If you >>don't have enough, you need to upgrade to servers with better i/o >>(i.e. not EC2: http://pl.atyp.us/wordpress/?p=3D2240&cpage=3D1) and/or >>more ram to cache the reads against. > > I agree that any given configuration will support a limited amount of I/O= . > > For the first few hours of my load test, I have enough I/O. =A0The proble= m is that Cassandra is spending too much I/O on reads and writes and too li= ttle on compactions to function well in the long term. If you don't have enough room for both, it doesn't matter how you prioritiz= e.