Return-Path: X-Original-To: apmail-cassandra-user-archive@www.apache.org Delivered-To: apmail-cassandra-user-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id B12F71029E for ; Thu, 10 Oct 2013 13:06:58 +0000 (UTC) Received: (qmail 51940 invoked by uid 500); 10 Oct 2013 13:06:53 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 51641 invoked by uid 500); 10 Oct 2013 13:06:50 -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 51629 invoked by uid 99); 10 Oct 2013 13:06:49 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 10 Oct 2013 13:06:48 +0000 X-ASF-Spam-Status: No, hits=1.5 required=5.0 tests=HTML_MESSAGE,RCVD_IN_DNSWL_LOW,SPF_PASS,T_REMOTE_IMAGE X-Spam-Check-By: apache.org Received-SPF: pass (nike.apache.org: domain of ken.hancock@schange.com designates 209.85.212.181 as permitted sender) Received: from [209.85.212.181] (HELO mail-wi0-f181.google.com) (209.85.212.181) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 10 Oct 2013 13:06:43 +0000 Received: by mail-wi0-f181.google.com with SMTP id l12so2255067wiv.2 for ; Thu, 10 Oct 2013 06:06:21 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:content-type; bh=pyLm0scCim4/UGQZknSH06f9SkPAJ+1QWmNLgA+0oMg=; b=MKcJUHoi3V5M0hqgCFSsyU1GGnC32clck8xW9UdatnQZeG96MRVMwwe2AeojX7uJ3U s0g9S2UrnK7Nre0njmdP5Ib8+c1O5SWYnhhOiZUfDGWSmimD+nCZYJmYlS+w5CL/+JF8 9lIC/1NJySzpXQtgKdBHD3cBsIyvZen05mzf/1hUrVwCwlhVQ+N9UUs/bt5uHXQQzQUP 0mVz7CFaaZqhvt0/BCVx6Wr+eDAlk614+3gZvt8ttBE03629XivHVs5MlBxyqpQ+ueDk x9jyAdANqm6GGh1+0hLuEa+9fYsGtylxHHzdN7g2XDaEh52Ah70Af02Htu4b9E5jiWfp 3eMg== X-Gm-Message-State: ALoCoQk9LVLFWaRUhXT58iOIMlewTzlUXW5BZUoCHxV/hrva7IQ/271nzeFAlOWxcxlU1bwYoMjY X-Received: by 10.180.160.165 with SMTP id xl5mr7668124wib.48.1381410381525; Thu, 10 Oct 2013 06:06:21 -0700 (PDT) MIME-Version: 1.0 Received: by 10.194.46.198 with HTTP; Thu, 10 Oct 2013 06:06:01 -0700 (PDT) In-Reply-To: <52568418.3010304@openmarket.com> References: <52568418.3010304@openmarket.com> From: Ken Hancock Date: Thu, 10 Oct 2013 09:06:01 -0400 Message-ID: Subject: Re: Rowcache and quorum reads cassandra To: user@cassandra.apache.org Content-Type: multipart/alternative; boundary=047d7b62509c1486ca04e862ab77 X-Virus-Checked: Checked by ClamAV on apache.org --047d7b62509c1486ca04e862ab77 Content-Type: text/plain; charset=ISO-8859-1 If you're hitting 3/5 nodes, it sounds like you've set your replication factor to 5. Is that what you're doing so you can have a 2-node outtage? For a 5-node cluster, RF=5, each node will have 100% of your data (a second DC is just a clone), so with a 3GB off-heap it means that 3GB / total would be cacheable in the row cache. On the other hand, if you're doing RF=3, each node will have 60% of your data instead of 100% so the effective percentage of rows that are cache goes up by 66%. Great quick & dirty caclulator: http://www.ecyrd.com/cassandracalculator/ On Thu, Oct 10, 2013 at 6:40 AM, Artur Kronenberg < artur.kronenberg@openmarket.com> wrote: > I was reading through configuration tips for cassandra and decided to > use row-cache in order to optimize the read performance on my cluster. > > I have a cluster of 10 nodes, each of them opeartion with 3 GB off-heap > using cassandra 2.4.1. I am doing local quorum reads, which means that I > will hit 3 nodes out of 5 because I split my 10 nodes into two data-centres. > > I was under the impression that since each node gets a certain range of > reads my total amount of off-heap would be 10 * 3 GB = 30 GB. However is > this still correct with quorum reads? How does cassandra handle row-cache > hits in combination with quorum reads? > > Thanks! > -- artur > -- *Ken Hancock *| System Architect, Advanced Advertising SeaChange International 50 Nagog Park Acton, Massachusetts 01720 ken.hancock@schange.com | www.schange.com | NASDAQ:SEAC Office: +1 (978) 889-3329 | [image: Google Talk:] ken.hancock@schange.com | [image: Skype:]hancockks | [image: Yahoo IM:]hancockks [image: LinkedIn] [image: SeaChange International] This e-mail and any attachments may contain information which is SeaChange International confidential. The information enclosed is intended only for the addressees herein and may not be copied or forwarded without permission from SeaChange International. --047d7b62509c1486ca04e862ab77 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable

If you're hitting 3/5 nodes, it sounds like = you've set your replication factor to 5. Is that what you're doing = so you can have a 2-node outtage?

For a 5-node cluster, RF=3D5= , each node will have 100% of your data (a second DC is just a clone), so w= ith a 3GB off-heap it means that 3GB / <total data size in GB> total = would be cacheable in the row cache.

On the other hand, if you're doing RF=3D3, each node will have 60% = of your data instead of 100% so the effective percentage of rows that are c= ache goes up by 66%.

Great quick & dirty caclulator: http://www.ecyrd.com/cassa= ndracalculator/

On Thu, Oct 10, 2013 at 6:40 AM, A= rtur Kronenberg <artur.kronenberg@openmarket.com> wrote:

=20 =20 =20
=20
I was reading through configuration tips for cassandra and decided to use row-cache in order to optimize the read performance on my cluster.

I have a cluster of 10 nodes, each of them opeartion with 3 GB off-heap using cassandra 2.4.1. I am doing local quorum reads, which means that I will hit 3 nodes out of 5 because I split my 10 nodes into two data-centres.

I was under the impression that since each node gets a certain range of reads my total amount of off-heap would be 10 * 3 GB =3D 30 GB. However is this still correct with quorum reads? How does cassandra handle row-cache hits in combination with quorum reads?

Thanks!
-- artur

--

Ken Hancock=A0\| System Architect, Advan= ced Advertising=A0 SeaChange International= =A0 50 Nagog Park Acton, Massachusetts 01720 ken.hancock@schange.com= =A0\|=A0www.schange.co= m=A0\| NASDAQ:SEAC=A0 Office: +1 (978) 889-3329=A0\|=A0=A0ken.hancock@schange.com=A0\|=A0hancockks=A0\|=A0hancockks

This e-mail and any attachments may contain information which is SeaChange= International confidential. The information enclosed is intended only for = the addressees herein and may not be copied or forwarded without permission= from SeaChange International.

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