Return-Path: Delivered-To: apmail-cassandra-user-archive@www.apache.org Received: (qmail 47332 invoked from network); 17 Aug 2010 19:09:41 -0000 Received: from unknown (HELO mail.apache.org) (140.211.11.3) by 140.211.11.9 with SMTP; 17 Aug 2010 19:09:41 -0000 Received: (qmail 45586 invoked by uid 500); 17 Aug 2010 19:09:40 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 45532 invoked by uid 500); 17 Aug 2010 19:09:39 -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 45524 invoked by uid 99); 17 Aug 2010 19:09:39 -0000 Received: from Unknown (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 17 Aug 2010 19:09:39 +0000 X-ASF-Spam-Status: No, hits=-0.0 required=10.0 tests=RCVD_IN_DNSWL_NONE,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (nike.apache.org: domain of ryan@twitter.com designates 74.125.82.44 as permitted sender) Received: from [74.125.82.44] (HELO mail-ww0-f44.google.com) (74.125.82.44) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 17 Aug 2010 19:09:32 +0000 Received: by wwi17 with SMTP id 17so1593541wwi.25 for ; Tue, 17 Aug 2010 12:09:12 -0700 (PDT) MIME-Version: 1.0 Received: by 10.227.72.149 with SMTP id m21mr5967073wbj.217.1282072152115; Tue, 17 Aug 2010 12:09:12 -0700 (PDT) Received: by 10.227.150.149 with HTTP; Tue, 17 Aug 2010 12:09:12 -0700 (PDT) In-Reply-To: References: Date: Tue, 17 Aug 2010 12:09:12 -0700 Message-ID: Subject: Re: cache sizes using percentages From: Ryan King To: user@cassandra.apache.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Virus-Checked: Checked by ClamAV on apache.org On Tue, Aug 17, 2010 at 10:55 AM, Artie Copeland w= rote: > if i set a key cache size of 100% the way i understand how that works is: > - the cache is not write through, but read through > - a key gets added to the cache on the first read if not already availabl= e > - the size of the cache will always increase for ever item read. =A0so if= you > have 100mil items your key cache will grow to 100mil > Here are my questions: > if that is the case then what happens if you only have enough mem to stor= e > 10mil items in your key cache? Then don't use a percentage. > do you lose the other 90% how is it determined what is removed? second-chance fifo. > will the server keep adding til it gets OOM? that or a gc storm > if you add a row cache as well how does that affect your percentage? > if there a priority between the cache? or are they independant so both wi= ll > try to be satisfied which would result in an OOM? they are independent -ryan