From user-return-64948-archive-asf-public=cust-asf.ponee.io@cassandra.apache.org Fri Jan 10 18:25:13 2020 Return-Path: X-Original-To: archive-asf-public@cust-asf.ponee.io Delivered-To: archive-asf-public@cust-asf.ponee.io Received: from mail.apache.org (hermes.apache.org [207.244.88.153]) by mx-eu-01.ponee.io (Postfix) with SMTP id B8B57180657 for ; Fri, 10 Jan 2020 19:25:12 +0100 (CET) Received: (qmail 1604 invoked by uid 500); 10 Jan 2020 18:25:07 -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 1541 invoked by uid 99); 10 Jan 2020 18:25:07 -0000 Received: from pnap-us-west-generic-nat.apache.org (HELO spamd3-us-west.apache.org) (209.188.14.142) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 10 Jan 2020 18:25:07 +0000 Received: from localhost (localhost [127.0.0.1]) by spamd3-us-west.apache.org (ASF Mail Server at spamd3-us-west.apache.org) with ESMTP id 76DA2181364 for ; Fri, 10 Jan 2020 18:25:06 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at spamd3-us-west.apache.org X-Spam-Flag: NO X-Spam-Score: 0.251 X-Spam-Level: X-Spam-Status: No, score=0.251 tagged_above=-999 required=6.31 tests=[DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_ENVFROM_END_DIGIT=0.25, HTML_MESSAGE=0.2, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=disabled Authentication-Results: spamd3-us-west.apache.org (amavisd-new); dkim=pass (2048-bit key) header.d=gmail.com Received: from mx1-ec2-va.apache.org ([10.40.0.8]) by localhost (spamd3-us-west.apache.org [10.40.0.10]) (amavisd-new, port 10024) with ESMTP id T5xQGkbmO4ZF for ; Fri, 10 Jan 2020 18:25:04 +0000 (UTC) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=209.85.166.52; helo=mail-io1-f52.google.com; envelope-from=chris.splinter114@gmail.com; receiver= Received: from mail-io1-f52.google.com (mail-io1-f52.google.com [209.85.166.52]) by mx1-ec2-va.apache.org (ASF Mail Server at mx1-ec2-va.apache.org) with ESMTPS id 2A4F5BC564 for ; Fri, 10 Jan 2020 18:25:04 +0000 (UTC) Received: by mail-io1-f52.google.com with SMTP id n21so3063866ioo.10 for ; Fri, 10 Jan 2020 10:25:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=KTYTDHdA1whbc3PIma7Eo1MkpLEQztxBjvw6DoGiMJM=; b=U6B2nANUiX4QfNmQv1ICup8Ou4hBwH2STppM+RcUJT5w995xnDf7a2d5QVbWUn4FCb Dk7vwIHUL6/3GhY7El33t4c9b5OdoNfetY3RgFJCYe/a33HFfj62Cdr1+MQyBpRNPr9V YZwN5tTAYUnVD3OqqnHv18rE79AsYeMIo1481lyfu73fjYxig6CQHK8BWbVVmLbSsKNy xJCM8e4p7uohlTB85hYa3+aPSS39czEGmIlDQLuXhlnF/h0Js5Fc2tTVqH7T//EMrpEz Gcf2hjCIVTwRbDBUqYuLvaCjdGs8hKkTROnyRy3dL57JkI1yCKAcQv7De3aZKj4T1Iwv 4tBw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=KTYTDHdA1whbc3PIma7Eo1MkpLEQztxBjvw6DoGiMJM=; b=tkn5NDkpaiyyOSDXVRADzbmFyHDyviyXYbGGZh8l07EkZyNPZyRJ7lHDCxts/TwKoB GN5TgB66UYraSgLmijar1OCM6LLu6jj+982PlAOKYmXLVWCtQAHHFhRh8r6Naqd5cHwt 0H9a83ZWIuL+t0eqA/RBPF08wLq2AeLtmd2YlJ2c/ieg4oWQ+f55I4n98dCm+sIbHID8 C2iHl2FDIs3/LSrFEv68LJm7R5QtvwklgU/wcQf5s7wWk1kjFO3ToAgcf4oPLeX9xKS3 t9Q1KZqnLXW2Aqg8/i/TGGTl0ZfkzLrGLoUYo7sWADtxLlOnlOOmNwk96DSOLCexKnUH nhjg== X-Gm-Message-State: APjAAAXh7QNYhY8bwJ//jhTukB9nPHiok3E9z4UT58WK+BOD4HKAamgq z/8k5Ub7WsEXUyx0Ol+U8F/9NeC8Sv3KBw/wPN80nIViJQc= X-Google-Smtp-Source: APXvYqzjV1OJSHEit9SeesSUVdrZOzP4Wc5kB8jQAL07n3jCeH4dBBv17x0oDtu26JKoVD0z/eaE8Bk5wFo16rEFliY= X-Received: by 2002:a6b:740c:: with SMTP id s12mr3840588iog.108.1578680703309; Fri, 10 Jan 2020 10:25:03 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Chris Splinter Date: Fri, 10 Jan 2020 12:24:52 -0600 Message-ID: Subject: Re: Replication system_distributed To: user@cassandra.apache.org Content-Type: multipart/alternative; boundary="00000000000088db84059bcd3e9b" --00000000000088db84059bcd3e9b Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi Marcel, The RF for that keyspace is currently hardcoded, see CASSANDRA-11098 . I am not sure why your RF switched from 1 to 3 after you restarted a cluster, I tried the same and it remained at 1 for me. The tables in that keyspace are used to store history about the repair operations, having it as RF=3D3 shouldn't affect the performance of the repair. See CASSANDRA-5839 for when / why it was introduced. Changing the replication from 3 to 1 for system_distributed is not a good idea for the same reasons why changing the replication of *any* keyspace to 1 is not a good idea. You lose the ability to query that data if a single node goes down. Hope this helps, Chris On Wed, Jan 8, 2020 at 1:23 AM Marcel Jakobi wrote: > Hi, > > > > the default definition of the keyspace system_distributed is: > > CREATE KEYSPACE system_distributed WITH replication =3D {'class': > 'SimpleStrategy', 'replication_factor': '3'} AND durable_writes =3D true= ; > > > > > > If I understand correctly, every repair information will be replicated on > three servers in the cluster. I have changed the RF to =E2=80=9A1=E2=80= =98. Once i stop the > entire cluster, the replication factor changes again to 3. It seems > Cassandra wants it to be 3. > > > > Doesn`t that reduce performance on repair operation? > > Why is the RF changed again after restart the cluster? > > Are there reasons why you shouldn`t change the replication factor to 1? > > > > Thanks, > > Marcel > --00000000000088db84059bcd3e9b Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Hi Marcel,

The RF for that keyspace is currently h= ardcoded, see CASSANDRA-11098. I am not sure why your RF switched from 1 to 3 af= ter you restarted a cluster, I tried the same and it remained at 1 for me.<= /div>

The tables in that keyspace are used to store hist= ory about the repair operations, having it as RF=3D3 shouldn't affect t= he performance of the repair. See CASSANDRA-5839 for when / why it was introduced= .
=C2=A0
Changing the replication from 3 to 1 for system_distributed = is not a good idea for the same reasons why changing the replication of = any keyspace to 1 is not a good idea. You lose the ability to query tha= t data if a single node goes down.

Hope this helps= ,

Chris=C2=A0
On Wed, = Jan 8, 2020 at 1:23 AM Marcel Jakobi <maj@ordix.de> wrote:

Hi,

=C2=A0

the default definition of the keyspace system_distri= buted is:

= CREATE KEYSPACE system_distributed WITH replication =3D {'class': &= #39;SimpleStrategy', 'replication_factor': '3'}=C2=A0 A= ND durable_writes =3D true;

= =C2=A0

= =C2=A0

If I un= derstand correctly, every repair information will be replicated on three se= rvers in the cluster. I have changed the RF to =E2=80=9A1=E2=80=98. Once i = stop the entire cluster, the replication factor changes again to 3. It seems Cassandra wants it to be 3.

= =C2=A0

Doesn`t= that reduce performance on repair operation?

Why is = the RF changed again after restart the cluster?

Are the= re reasons why you shouldn`t change the replication factor to 1?<= /u>

= =C2=A0

Thanks,=

Marcel<= u>

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