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Date: Fri, 07 Mar 2014 07:41:13 -0800
From: Daniel Curry <daniel.curry@arrayent.com>
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Subject: Re: replication_factor: ?
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Thank you.  Your answer makes sense, Is this documented any where

On 03/07/2014 07:37 AM, John Pyeatt wrote:
> You really don't want to set your RF to the same value as the number 
> of nodes in your cluster for a variety of reasons. The biggest one 
> being that if you have a node go down, your entire database is 
> essentially down because you will be unable to fulfil any requests 
> because the RF can never be met.
>
> The number of nodes in the cluster is essentially independent from 
> your replication factor.
>
> The more important relationship is between your RF value, latency, and 
> what consistency level you want to use for your reads and writes.
>
> If you are going to use QUORUM consistency level it makes a little 
> more sense to have your RF set to an odd number.
>
> So for example if you have a 12 node cluster with an RF=3 and you are 
> using QUORUM consistency that means that 2 nodes ((RF+1)/2) have to be 
> able to fulfil the request.
>
>
>
> On Fri, Mar 7, 2014 at 9:26 AM, Daniel Curry 
> <daniel.curry@arrayent.com <mailto:daniel.curry@arrayent.com>> wrote:
>
>       I would like to know on what is the rule of thumb for
>     "replication_factor:" number?
>     I think the answer is depends on how many nodes one has? IE: three
>     nodes will be the
>     number 3.  What would happen it I put the number 2 for a three
>     node cluster?
>        We are using both 3.2.4 and 3.1.3 ( that will be upgraded to
>     3.2.4).
>
>     Thank you.
>
>     -- 
>     Daniel Curry
>
>     Sr. Linux System Administrator, Network Operations
>
>     PGP : AD5A 96DC 7556 A020 B8E7 0E4D 5D5E 9BA5 C83E 8C92
>
>     Arrayent, Inc.
>     2317 Broadway Street, Suite 20
>     Redwood City, CA 94063
>     daniel@arrayent.com <mailto:daniel@arrayent.com>
>     650-260-4520 <tel:650-260-4520>
>
>
>
>
> -- 
> John Pyeatt
> Singlewire Software, LLC
> www.singlewire.com <http://www.singlewire.com/>
> ------------------
> 608.661.1184
> john.pyeatt@singlewire.com <mailto:john.pyeatt@singlewire.com>

-- 
Daniel Curry

Sr. Linux System Administrator, Network Operations

PGP : AD5A 96DC 7556 A020 B8E7 0E4D 5D5E 9BA5 C83E 8C92

Arrayent, Inc.
2317 Broadway Street, Suite 20
Redwood City, CA 94063
daniel@arrayent.com
650-260-4520


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    Thank you.&nbsp; Your answer makes sense, Is this documented any where<br>
    <br>
    <div class="moz-cite-prefix">On 03/07/2014 07:37 AM, John Pyeatt
      wrote:<br>
    </div>
    <blockquote
cite="mid:CAEisTLnnGnTdfDoVFOh7xJwMJdRUwtLwe85HKXTss_40Uv3xdQ@mail.gmail.com"
      type="cite">
      <div dir="ltr">
        <div>You really don't want to set your RF to the same value as
          the number of nodes in your cluster for a variety of reasons.
          The biggest one being that if you have a node go down, your
          entire database is essentially down because you will be unable
          to fulfil any requests because the RF can never be met.<br>
          <br>
          The number of nodes in the cluster is essentially independent
          from your replication factor.<br>
          <br>
        </div>
        <div>The more important relationship is between your RF value,
          latency, and what consistency level you want to use for your
          reads and writes.<br>
          <br>
        </div>
        <div>If you are going to use QUORUM consistency level it makes a
          little more sense to have your RF set to an odd number.<br>
          <br>
          So for example if you have a 12 node cluster with an RF=3 and
          you are using QUORUM consistency that means that 2 nodes
          ((RF+1)/2) have to be able to fulfil the request.<br>
          <br>
        </div>
      </div>
      <div class="gmail_extra"><br>
        <br>
        <div class="gmail_quote">On Fri, Mar 7, 2014 at 9:26 AM, Daniel
          Curry <span dir="ltr">&lt;<a moz-do-not-send="true"
              href="mailto:daniel.curry@arrayent.com" target="_blank">daniel.curry@arrayent.com</a>&gt;</span>
          wrote:<br>
          <blockquote class="gmail_quote" style="margin:0 0 0
            .8ex;border-left:1px #ccc solid;padding-left:1ex">&nbsp; I would
            like to know on what is the rule of thumb for
            "replication_factor:" number?<br>
            I think the answer is depends on how many nodes one has? IE:
            three nodes will be the<br>
            number 3. &nbsp;What would happen it I put the number 2 for a
            three node cluster?<br>
            &nbsp; &nbsp;We are using both 3.2.4 and 3.1.3 ( that will be upgraded
            to 3.2.4).<br>
            <br>
            Thank you.<span class="HOEnZb"><font color="#888888"><br>
                <br>
                -- <br>
                Daniel Curry<br>
                <br>
                Sr. Linux System Administrator, Network Operations<br>
                <br>
                PGP : AD5A 96DC 7556 A020 B8E7 0E4D 5D5E 9BA5 C83E 8C92<br>
                <br>
                Arrayent, Inc.<br>
                2317 Broadway Street, Suite 20<br>
                Redwood City, CA 94063<br>
                <a moz-do-not-send="true"
                  href="mailto:daniel@arrayent.com" target="_blank">daniel@arrayent.com</a><br>
                <a moz-do-not-send="true" href="tel:650-260-4520"
                  value="+16502604520" target="_blank">650-260-4520</a><br>
                <br>
              </font></span></blockquote>
        </div>
        <br>
        <br clear="all">
        <br>
        -- <br>
        John Pyeatt<br>
        Singlewire Software, LLC<br>
        <a moz-do-not-send="true" href="http://www.singlewire.com/"
          target="_blank">www.singlewire.com</a><br>
        ------------------<br>
        608.661.1184<br>
        <font color="#888888">
          <a moz-do-not-send="true"
            href="mailto:john.pyeatt@singlewire.com" target="_blank">john.pyeatt@singlewire.com</a></font>
      </div>
    </blockquote>
    <br>
    <pre class="moz-signature" cols="72">-- 
Daniel Curry

Sr. Linux System Administrator, Network Operations

PGP : AD5A 96DC 7556 A020 B8E7 0E4D 5D5E 9BA5 C83E 8C92

Arrayent, Inc.
2317 Broadway Street, Suite 20
Redwood City, CA 94063
<a class="moz-txt-link-abbreviated" href="mailto:daniel@arrayent.com">daniel@arrayent.com</a>
650-260-4520
</pre>
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