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 6EAFCDABD for ; Sat, 5 Jan 2013 00:57:42 +0000 (UTC) Received: (qmail 7732 invoked by uid 500); 5 Jan 2013 00:57:39 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 7692 invoked by uid 500); 5 Jan 2013 00:57:39 -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 7682 invoked by uid 99); 5 Jan 2013 00:57:39 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Sat, 05 Jan 2013 00:57:39 +0000 X-ASF-Spam-Status: No, hits=1.7 required=5.0 tests=FREEMAIL_ENVFROM_END_DIGIT,HTML_MESSAGE,RCVD_IN_DNSWL_LOW,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (nike.apache.org: domain of owenzhang1990@gmail.com designates 74.125.83.47 as permitted sender) Received: from [74.125.83.47] (HELO mail-ee0-f47.google.com) (74.125.83.47) by apache.org (qpsmtpd/0.29) with ESMTP; Sat, 05 Jan 2013 00:57:34 +0000 Received: by mail-ee0-f47.google.com with SMTP id e51so8151793eek.6 for ; Fri, 04 Jan 2013 16:57:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=1FSIWk3vqGwY19aV9QBvIJ6B2uQ4t1BiLrKBcNeoF4c=; b=rDyX9fi73Q2ECc7fWrH/IzpLvBIbk9i69BfBlAx7QYT4eNmkOj5r7KwKnYmEFm9DJb NRnXmxsuXCji8jmze79J+Zw87oSyAykqQrtSDbCQalpMh6rf3FTsZ2s60vLUlw+lZQzG NrYK2bVkBCtpgzSkB4HaJdumW0XzruG5qXBBGGjMlUtogxYlW4NT6bA3vRii5ZOLlvQk nL19YD/vCUTDSRWi2wgM1Xy8la+16MZe9l4eq2D1414NYGgNeSloVuSUDC48BuV5HZEi rq8wEda42mnYFnfnCkqQufJImqCZ95GhbYFMXzWmqg9O/qIJLH1FFUKSvuW2mijKNMuE 9BLQ== MIME-Version: 1.0 Received: by 10.14.176.66 with SMTP id a42mr147330062eem.34.1357347434074; Fri, 04 Jan 2013 16:57:14 -0800 (PST) Received: by 10.14.177.71 with HTTP; Fri, 4 Jan 2013 16:57:13 -0800 (PST) In-Reply-To: References: Date: Sat, 5 Jan 2013 08:57:13 +0800 Message-ID: Subject: Re: num_tokens - virtual nodes From: Manu Zhang To: user@cassandra.apache.org Content-Type: multipart/alternative; boundary=047d7b6222d0a5143104d28013d5 X-Virus-Checked: Checked by ClamAV on apache.org --047d7b6222d0a5143104d28013d5 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable https://www.youtube.com/watch?v=3DGddZ3pXiDys&list=3DPLC5E3906433F5A165&ind= ex=3D28 This video of Cassandra summit 2012 has mentioned the use of 256 tokens by default (though it's no longer in the conf/cassandra.yaml). I remember that more tokens could lead to more disk seeks or something. I think 256 is an empirical number based on tests of the speaker. Here are two more related articles that you want to read. http://www.acunu.com/2/post/2012/07/virtual-nodes-strategies.html http://www.acunu.com/2/post/2012/10/improving-cassandras-uptime-with-virtua= l-nodes.html On Sat, Jan 5, 2013 at 12:18 AM, Michael Kjellman wrote: > http://www.mail-archive.com/user@cassandra.apache.org/msg26528.html > > From: Alain RODRIGUEZ > Reply-To: "user@cassandra.apache.org" > Date: Friday, January 4, 2013 6:00 AM > To: "user@cassandra.apache.org" > Subject: num_tokens - virtual nodes > > Hi, > > I just discover the vnodes new feature described here: > http://www.datastax.com/dev/blog/virtual-nodes-in-cassandra-1-2 > > In the post above, Brandon says "If you=92d like to upgrade an installati= on > to virtual nodes, that=92s possible too, but I=92ll save that for a later > post". Does this post now exist somewhere ? > > From the cassandra.yaml: > > # If you already have a cluster with 1 token per node, and wish to migrat= e > to > # multiple tokens per node, see > http://wiki.apache.org/cassandra/Operations > # num_tokens: 256 > > I see no reference to vnodes or num_tokens on this wiki. > > So, how to switch from "physical" nodes to vnodes ? > > This is useful only if your number of nodes is greater than the RF, right= ? > > Why 256 token by default ? Where this value come from ? > > Is there more advantage / disadvantage of using vnodes that improving the > internodes data streaming by increasing the number of data sources ? > > Alain > > ---------------------------------- > Join Barracuda Networks in the fight against hunger. > To learn how you can help in your community, please visit: > http://on.fb.me/UAdL4f > =AD=AD > --047d7b6222d0a5143104d28013d5 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable
https://www.youtube.com/watch?= v=3DGddZ3pXiDys&list=3DPLC5E3906433F5A165&index=3D28=A0This vid= eo of Cassandra summit 2012 has mentioned the use of 256 tokens by default = (though it's no longer in the conf/cassandra.yaml). I remember that mor= e tokens could lead to more disk seeks or something. I think 256 is an empi= rical number based on tests of the speaker.=A0

Here are two more related articles that you want = to read.=A0


On Sat, Jan 5, 2013 at 12:18 AM, Michael= Kjellman <mkjellman@barracuda.com> wrote:

From: Alain RODRIGUEZ <arodrime@gmail.com>=
Reply-To: "user@cassandra.apache.org<= /a>" <user@cassandra.apache.org>
Date: Friday, January 4, 2013 6:00= AM
To: "user@cassandra.apache.org= " <u= ser@cassandra.apache.org>
Subject: num_tokens - virtual node= s

Hi,

I just discover the vnodes new feature described here:= =A0http://www.datastax.com/dev/blog/virtual-nodes-in-cas= sandra-1-2

In the post above, Brandon says "If yo= u=92d like to upgrade an installation to virtual nodes, that=92s possible t= oo, but I=92ll save that for a later post". Does this post now exist somewhere ?

From the cassandra.yaml:

# If you alre= ady have a cluster with 1 token per node, and wish to migrate to
# multiple tokens per node, see http://wiki.apache.org/cassandra/Operations
# num_tokens: 256=

I see no reference to vnodes or num_tokens on thi= s wiki.

So, how to switch from "physical"= ; nodes to vnodes ?

This is useful only if your number of nodes is greater = than the RF, right ?

Why 256 token by default ? Wh= ere this value come from ?

Is there more advantage= / disadvantage of using vnodes that improving the internodes data streamin= g by increasing the number of data sources ?

Alain
<= br>
----------------------------------
Join Barracuda Networks in the fight against hunger.
To learn how you can help in your community, please visit: http://on.fb.me/UAdL4f
=A0=A0=AD=AD=A0=A0

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