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List:       cassandra-user
Subject:    Re: Multiple cassandra instances per physical node
From:       Ben Bromhead <ben () instaclustr ! com>
Date:       2015-05-26 16:08:10
Message-ID: CAA=6J09-NUeoJum3HsKwJ94ood7Ww1Ks2BHq6c7E6boqpsL4UA () mail ! gmail ! com
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@Sean -> You can manually change the ports used by Datastax agent using the
address.yaml file in the agent install directory.

+1 on using racks to separate it out... but it will increase operational
complexity somewhat

On 26 May 2015 at 08:11, Nate McCall <nate@thelastpickle.com> wrote:

>
>> If you're running multiple nodes on a single server, vnodes give you no
>> control over which instance has which key (whereas you can assign initial
>> tokens).  Therefore you could have two of your three replicas on the same
>> physical server which, if it goes down, you can't read or write at quorum.
>>
>
> Yep. You *will* have overlapping ranges on each physical server so long as
> Vnodes > 'number of nodes in the cluster'.
>
>
>
>>
>> However, can't you use the topology snitch to put both nodes in the same
>> rack?  Won't that prevent the issue and still allow you to maintain quorum
>> if a single server goes down?  If I have a 20-node cluster with 2 nodes on
>> each physical server, can I use 10 racks to properly segment my partitions?
>>
>
> That's a good point, yes. I'd still personally prefer the operational
> simplicity of simply spacing out token assignments though, but YMMV.
>
>
>
> --
> -----------------
> Nate McCall
> Austin, TX
> @zznate
>
> Co-Founder & Sr. Technical Consultant
> Apache Cassandra Consulting
> http://www.thelastpickle.com
>



-- 

Ben Bromhead

Instaclustr | www.instaclustr.com | @instaclustr
<http://twitter.com/instaclustr> | (650) 284 9692

[Attachment #3 (text/html)]

<div dir="ltr">@Sean -&gt; You can manually change the ports used by Datastax agent \
using the address.yaml file in the agent install directory.<div><br></div><div>+1 on \
using racks to separate it out... but it will increase operational complexity \
somewhat</div></div><div class="gmail_extra"><br><div class="gmail_quote">On 26 May \
2015 at 08:11, Nate McCall <span dir="ltr">&lt;<a \
href="mailto:nate@thelastpickle.com" \
target="_blank">nate@thelastpickle.com</a>&gt;</span> wrote:<br><blockquote \
class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc \
solid;padding-left:1ex"><div dir="ltr"><div class="gmail_extra"><div \
class="gmail_quote"><span class=""><blockquote class="gmail_quote" style="margin:0 0 \
0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div \
dir="ltr"><div><br></div><div>If you&#39;re running multiple nodes on a single \
server, vnodes give you no control over which instance has which key (whereas you can \
assign initial tokens).   Therefore you could have two of your three replicas on the \
same physical server which, if it goes down, you can&#39;t read or write at \
quorum.<br></div></div></blockquote><div><br></div></span><div>Yep. You *will* have \
overlapping ranges on each physical server so long as Vnodes &gt; &#39;number of \
nodes in the cluster&#39;.   </div><span class=""><div><br></div><div>  \
</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc \
solid;padding-left:1ex"><div dir="ltr"><div><br></div><div>However, can&#39;t you use \
the topology snitch to put both nodes in the same rack?   Won&#39;t that prevent the \
issue and still allow you to maintain quorum if a single server goes down?   If I \
have a 20-node cluster with 2 nodes on each physical server, can I use 10 racks to \
properly segment my partitions?<br></div></div></blockquote><div><br></div></span><div>That&#39;s \
a good point, yes. I&#39;d still personally prefer the operational simplicity of \
simply spacing out token assignments though, but YMMV.  </div><div><br></div><div>  \
</div><div><br></div></div><span class="">-- <br><div><div \
dir="ltr">-----------------<br>Nate McCall<br>Austin, TX<br>@zznate<br><br>Co-Founder \
&amp; Sr. Technical Consultant<br>Apache Cassandra Consulting<br><a \
href="http://www.thelastpickle.com" \
target="_blank">http://www.thelastpickle.com</a></div></div> </span></div></div>
</blockquote></div><br><br clear="all"><div><br></div>-- <br><div \
class="gmail_signature"><div dir="ltr"><div><div dir="ltr">







<p>Ben Bromhead</p>
<p>Instaclustr |  <a href="https://www.instaclustr.com/" \
target="_blank"><span>www.instaclustr.com</span></a>  |  <a \
href="http://twitter.com/instaclustr" target="_blank"><span>@instaclustr</span></a>  \
| (650) 284 9692<br></p></div></div></div></div> </div>



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