From user-return-17065-apmail-cassandra-user-archive=cassandra.apache.org@cassandra.apache.org Wed May 25 03:46:42 2011 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 85F8841D3 for ; Wed, 25 May 2011 03:46:42 +0000 (UTC) Received: (qmail 41946 invoked by uid 500); 25 May 2011 03:46:40 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 41395 invoked by uid 500); 25 May 2011 03:46:39 -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 41383 invoked by uid 99); 25 May 2011 03:46:37 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 25 May 2011 03:46:37 +0000 X-ASF-Spam-Status: No, hits=2.2 required=5.0 tests=HTML_MESSAGE,MIME_QP_LONG_LINE,RCVD_IN_DNSWL_NONE,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: local policy) Received: from [208.113.200.5] (HELO homiemail-a80.g.dreamhost.com) (208.113.200.5) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 25 May 2011 03:46:31 +0000 Received: from homiemail-a80.g.dreamhost.com (localhost [127.0.0.1]) by homiemail-a80.g.dreamhost.com (Postfix) with ESMTP id 0492937A065 for ; Tue, 24 May 2011 20:45:36 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; c=nofws; d=thelastpickle.com; h=to:from :subject:date:message-id:content-type:mime-version:in-reply-to; q=dns; s=thelastpickle.com; b=aC9doUsHdB7o4+DS6TPd7HoOvT3MC5E6d e4RqhgJa6uL37ekal0C3mm9BMOEN0W74aekaP/0z3HD6bls2SgDDdcO0j7p7SMsZ Wiq6qIlcUYZ6rm3+m7SqjeNF7VY0ZchoQtBzH0pUFvqoWILifGsxFmt7vFSs5aqC r3ISwcs934= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=thelastpickle.com; h=to :from:subject:date:message-id:content-type:mime-version: in-reply-to; s=thelastpickle.com; bh=1cFDNY7mT7eolJZZrGJAO59dE4Y =; b=JGIga9ozu7iImZsnH28xqEP/XQkZ7Gqn+KgE/0DktjyhER7Anco6IVs25bA TvzoxbH0PAxumEjFbMyIImBUfyf0R60KrK7t7XvlcqLsp/agpHYJxNXU/k7/Mzqj 3vlfRjtE+oCDq494wXTaJKVmqlod+HCftwOiQ1EsbT07e0Nk= Received: from localhost (webms.mac.com [17.148.16.116]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: aaron@thelastpickle.com) by homiemail-a80.g.dreamhost.com (Postfix) with ESMTPSA id E59FE37A020 for ; Tue, 24 May 2011 20:45:35 -0700 (PDT) To: user@cassandra.apache.org From: Aaron Morton Subject: Re: Measure Latency Date: Wed, 25 May 2011 03:46:06 GMT X-Mailer: MobileMe Mail (1C3224) Message-id: <4b7a07c8-09b2-640e-f206-c5a142fa9b65@me.com> Content-Type: multipart/alternative; boundary=Apple-Webmail-42--170e5887-1c26-447b-dfa4-8501c8fe5f28 MIME-Version: 1.0 In-Reply-To: --Apple-Webmail-42--170e5887-1c26-447b-dfa4-8501c8fe5f28 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252; format=flowed Once the cluster has returned to the client you know the write has been co= mmitted to Consistency Level =A0number of nodes.=A0=0A=0Ai.e. If you send = an insert using QUORUM consistency to a cluster with Replication Factor 3,= and you get a non error response you know the write has occurred on at le= ast 2 nodes (one may be the one the client is connected to.)=0A=0AAfter th= e initial request has completed it's up the "Eventual Consistency" feature= s of Read Repair, Hinted Handoff and Anti-Entropy to distribute changes.=A0= =0A=0ADoes that help or are you thinking of something else? =A0=0A--------= ---------=0AAaron Morton=0AFreelance Cassandra Developer=0A@aaronmorton=0A= http://www.thelastpickle.com=0A=0AOn 25 May, 2011,at 03:11 PM, Stephan Pfa= mmatter wrote:=0A=0AWhat=92s the recommended way o= f measuring latency between nodes in a cluster?=0ABy that I=92m not referr= ing to read/write latency for a given KS/CF. =0ABasically I want to inject= a row in a node A and want to see how long it takes to get to node B (ass= uming proper RF is set). =0A=0AI have already some network monitoring in o= ur windows environment between my distributed nodes in place. But I still = would like to get a handle on how a potential network and/or cassandra slo= wness affects inter-node latency. Maybe there is a tool/cmd that I'm not a= ware of? Tx.=0A=0A --Apple-Webmail-42--170e5887-1c26-447b-dfa4-8501c8fe5f28 Content-Type: multipart/related; type="text/html"; boundary=Apple-Webmail-86--170e5887-1c26-447b-dfa4-8501c8fe5f28 --Apple-Webmail-86--170e5887-1c26-447b-dfa4-8501c8fe5f28 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=windows-1252;
Once the cluster has returned to the client you know the write has be= en committed to Consistency Level  number of nodes. 
<= br>
i.e. If you send an insert using QUORUM consistency to a clu= ster with Replication Factor 3, and you get a non error response you know = the write has occurred on at least 2 nodes (one may be the one the client = is connected to.)

After the initial request has c= ompleted it's up the "Eventual Consistency" features of Read Repair, Hinte= d Handoff and Anti-Entropy to distribute changes. 

Does that help or are you thinking of something else?  
<= div>
-----------------=0AAaron Morton=0AFreelance Cassandra Developer=0A@aaron=
morton=0Ahttp://www.thelastpickle.com

On 25 May, 2011,= at 03:11 PM, Stephan Pfammatter <steplmi4124@gmail.com> wrote:
What=92s the rec= ommended way of measuring=0Alatency between nodes in a cluster?=0A=0A

By that I=92m not referring to read/write latency=0Afor a give= n KS/CF.

Basically I want to inject a row in a node A a= nd want to see how=0Along it takes to get to node B (assuming proper RF is= set).


I have already some net= work monitoring in our windows environment between my distributed nodes in= place. But I still would like to get a handle on how a potential network = and/or cassandra slowness affects inter-node latency. Maybe there is a too= l/cmd that I'm not aware of? Tx.
=0A


=0A=0A
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