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 822A897B7 for ; Wed, 18 Jul 2012 06:51:15 +0000 (UTC) Received: (qmail 66127 invoked by uid 500); 18 Jul 2012 06:51:13 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 66009 invoked by uid 500); 18 Jul 2012 06:51:12 -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 65980 invoked by uid 99); 18 Jul 2012 06:51:11 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 18 Jul 2012 06:51:11 +0000 X-ASF-Spam-Status: No, hits=1.5 required=5.0 tests=FSL_RCVD_USER,HTML_MESSAGE,RCVD_IN_DNSWL_LOW,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: domain of ares.tang@gmail.com designates 209.85.160.172 as permitted sender) Received: from [209.85.160.172] (HELO mail-gh0-f172.google.com) (209.85.160.172) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 18 Jul 2012 06:51:06 +0000 Received: by ghbg16 with SMTP id g16so1365753ghb.31 for ; Tue, 17 Jul 2012 23:50:45 -0700 (PDT) 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=3LebFMQ26C5MHOMwG0f7VHZYN5q2sjp9AkVJGgNI2HE=; b=za5gdGxFK87IXFPyXjya3VI84mctZVY+og0GDnuA/XbMmboWk4DRYa9zfY2ZEy2p9n j28fpfGLEH7fLG0fUmltYRpiDF1JWqvLNYlmSDD4/DTfEkY7cUzGF/T4xh0+3uleJgz6 hTDd+eq+aUVW3hhiFcXMCOgiZELNjkcsTIWaow1OIlxwO779D1VCNi7FSHWqixEQn6hM KQaL4oCuuKLhMyGtHgFzQbJaA53lTYc/bMDaTx9vfbzsyNxb2wnyiorOGDGa6fmeq7P+ LyEUqkJtOsTTLWGOcv45jlNi1Thkkij+JxIDev7i/e6QSvkOfDpDDJuAIVf1v4tNSFp+ Yrmw== MIME-Version: 1.0 Received: by 10.50.237.39 with SMTP id uz7mr933554igc.4.1342594245654; Tue, 17 Jul 2012 23:50:45 -0700 (PDT) Received: by 10.50.183.170 with HTTP; Tue, 17 Jul 2012 23:50:45 -0700 (PDT) In-Reply-To: <008501cd6490$4c049790$e40dc6b0$@itscape.com> References: <008001cd643e$00129460$0037bd20$@itscape.com> <008501cd6490$4c049790$e40dc6b0$@itscape.com> Date: Wed, 18 Jul 2012 14:50:45 +0800 Message-ID: Subject: Re: Replication factor - Consistency Questions From: Jason Tang To: user@cassandra.apache.org Content-Type: multipart/alternative; boundary=f46d044787ff16f86504c51515fd X-Virus-Checked: Checked by ClamAV on apache.org --f46d044787ff16f86504c51515fd Content-Type: text/plain; charset=ISO-8859-1 Yes, for ALL, it is not good for HA, and because we meet problem when use QUORAM, and current solution is switch Write:QUORAM / Read:QUORAM when got "UnavailableException" exception. 2012/7/18 Jay Parashar > Thanks..but write ALL will fail for any downed nodes. I am thinking of > QUORAM.**** > > ** ** > > *From:* Jason Tang [mailto:ares.tang@gmail.com] > *Sent:* Tuesday, July 17, 2012 8:24 PM > *To:* user@cassandra.apache.org > *Subject:* Re: Replication factor - Consistency Questions**** > > ** ** > > Hi**** > > ** ** > > I am starting using Cassandra for not a long time, and also have problems > in consistency.**** > > ** ** > > Here is some thinking.**** > > If you have Write:Any / Read:One, it will have consistency problem, and if > you want to repair, check your schema, and check the parameter "Read repair > chance: "**** > > http://wiki.apache.org/cassandra/StorageConfiguration **** > > ** ** > > And if you want to get consistency result, my suggestion is to have > Write:ALL / Read:One, since for Cassandra, write is more faster then read. > **** > > ** ** > > For performance impact, you need to test your traffic, and if your memory > can not cache all your data, or your network is not fast enough, then yes, > it will impact to write one more node.**** > > ** ** > > BRs**** > > ** ** > > 2012/7/18 Jay Parashar **** > > Hello all, > > There is a lot of material on Replication factor and Consistency level but > I > am a little confused by what is happening on my setup. (Cassandra 1.1.2). I > would appreciate any answers. > > My Setup: A cluster of 2 nodes evenly balanced. My RF =2, Consistency > Level; > Write = ANY and Read = 1 > > I know that my consistency is Weak but since my RF = 2, I thought data > would > be just duplicated in both the nodes but sometimes, querying does not give > me the correct (or gives partial) results. In other times, it gives me the > right results > Is the Read Repair going on after the first query? But as RF = 2, data is > duplicated then why the repair? > Note: My query is done a while after the Writes so data should have been in > both the nodes. Or is this not the case (flushing not happening etc)? > > I am thinking of making the Write as 1 and Read as QUORAM so R + W > RF (1 > + > 2 > 2) to give strong consistency. Will that affect performance a lot > (generally speaking)? > > Thanks in advance > Regards > > Jay > > **** > > ** ** > --f46d044787ff16f86504c51515fd Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Yes, for ALL, it is not good for HA, and because we meet problem when use Q= UORAM, and current solution is switch Write:QUORAM / Read:QUORAM when got &= quot;UnavailableException" exception.

2012/7/18 Jay Parashar <jparashar@itscape.com>

Thanks..but write ALL will fail for any down= ed nodes. I am thinking of QUORAM.

=A0<= /p>

From: Jason= Tang [mailto:ares= .tang@gmail.com]
Sent: Tuesday, July 17, 2012 8:24 PM
To: user@cassandra.apache.org=
Subject: Re: Replication factor - Consistency Questions

=A0

Hi

=A0

I am starting using Cassandra fo= r not a long time, and also have problems in consistency.

=A0

Here is some thinking.

If you have Write:Any / Read:One, it will have consistency p= roblem, and if you want to repair, check your schema, and check the paramet= er "Read repair chance: "

=A0

And if you want to get consistency result= , my suggestion is to have Write:ALL / Read:One, since for Cassandra, write= is more faster then read.

=A0

For performance impa= ct, you need to test your traffic, and if your memory can not cache all you= r data, or your network is not fast enough, then yes, it will impact to wri= te one more node.

=A0

BRs

=A0

= 2012/7/18 Jay Parashar <jparashar@itscape.com>

Hello all,

The= re is a lot of material on Replication factor and Consistency level but Iam a little confused by what is happening on my setup. (Cassandra 1.1.2).= I
would appreciate any answers.

My Setup: A cluster of 2 nodes evenly = balanced. My RF =3D2, Consistency Level;
Write =3D ANY and Read =3D 1
I know that my consistency is Weak but since my RF =3D 2, I thought da= ta would
be just duplicated in both the nodes but sometimes, querying does not give<= br>me the correct (or gives partial) results. In other times, it gives me t= he
right results
Is the Read Repair going on after the first query? B= ut as RF =3D 2, data is
duplicated then why the repair?
Note: My query is done a while after the= Writes so data should have been in
both the nodes. Or is this not the c= ase (flushing not happening etc)?

I am thinking of making the Write = as 1 and Read as QUORAM so R + W > RF (1 +
2 > 2) to give strong consistency. Will that affect performance a lot(generally speaking)?

Thanks in advance
Regards

Jay

=A0

<= /blockquote>

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