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From: Aaron Morton <aaron@thelastpickle.com>
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Subject: Re: cassandra 1.2.5- virtual nodes (num_token) pros/cons?
Date: Tue, 13 Aug 2013 09:09:43 +1200
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> Aaron - I read about the virtual nodes at =
http://www.datastax.com/dev/blog/virtual-nodes-in-cassandra-1-2

Thanks, I did not see anything in there about making repair smoother / =
faster.=20

Cheers
A
-----------------
Aaron Morton
Cassandra Consultant
New Zealand

@aaronmorton
http://www.thelastpickle.com

On 10/08/2013, at 11:39 AM, rash aroskar <rashmi.aroskar@gmail.com> =
wrote:

> Aaron - I read about the virtual nodes at =
http://www.datastax.com/dev/blog/virtual-nodes-in-cassandra-1-2
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
> On Tue, Aug 6, 2013 at 4:49 AM, Richard Low <richard@wentnet.com> =
wrote:
> On 6 August 2013 08:40, Aaron Morton <aaron@thelastpickle.com> wrote:
>> The reason for me looking at virtual nodes is because of terrible =
experiences we had with 0.8 repairs and as per documentation (an =
logically) the virtual nodes seems like it will help repairs being =
smoother. Is this true?
> I've not thought too much about how they help repair run smoother, =
what was the documentation you read ?=20
>=20
> There might be a slight improvement but I haven't observed any.  The =
difference might be that, because every node shares replicas with every =
other (with high probability), a single repair operation does the same =
work on the node it was called on, but the rest is spread out over the =
cluster, rather than just the RF nodes either side of the repairing =
node.  This means the post-repair compaction work will take less time =
and the length of time a node is loaded for during repair is less.
>=20
> However, the other benefits of vnodes are likely to be much more =
useful.
>=20
> Richard.
>=20


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<html><head><meta http-equiv="Content-Type" content="text/html charset=iso-8859-1"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><blockquote type="cite"><div dir="ltr">Aaron - I read about the virtual nodes at&nbsp;<a href="http://www.datastax.com/dev/blog/virtual-nodes-in-cassandra-1-2" target="_blank">http://www.datastax.com/dev/blog/virtual-nodes-in-cassandra-1-2</a></div></blockquote><div><br></div><div>Thanks, I did not see anything in there about making repair smoother / faster.&nbsp;</div><div><br></div><div>Cheers</div><div>A</div><div apple-content-edited="true">
<div><div>-----------------</div><div>Aaron Morton</div><div>Cassandra Consultant</div><div>New Zealand</div><div><br></div><div>@aaronmorton</div><div><a href="http://www.thelastpickle.com">http://www.thelastpickle.com</a></div></div>

</div>
<br><div><div>On 10/08/2013, at 11:39 AM, rash aroskar &lt;<a href="mailto:rashmi.aroskar@gmail.com">rashmi.aroskar@gmail.com</a>&gt; wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr">Aaron - I read about the virtual nodes at&nbsp;<a href="http://www.datastax.com/dev/blog/virtual-nodes-in-cassandra-1-2" target="_blank">http://www.datastax.com/dev/blog/virtual-nodes-in-cassandra-1-2</a><div><br>
</div><div><br></div><div><br></div><div><br></div><div><br><div><br></div></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Aug 6, 2013 at 4:49 AM, Richard Low <span dir="ltr">&lt;<a href="mailto:richard@wentnet.com" target="_blank">richard@wentnet.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="im">On 6 August 2013 08:40, Aaron Morton <span dir="ltr">&lt;<a href="mailto:aaron@thelastpickle.com" target="_blank">aaron@thelastpickle.com</a>&gt;</span> wrote:<br>
</div><div class="gmail_extra"><div class="gmail_quote"><div class="im">

<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div><blockquote type="cite"><div dir="ltr">The reason for me looking at virtual nodes is because of terrible experiences we had with 0.8 repairs and as per documentation (an logically) the virtual nodes seems like it will help repairs being smoother. Is this true?</div>


</blockquote></div>I've not thought too much about how they help repair run smoother, what was the documentation you read ?&nbsp;</div></blockquote><div><br></div></div><div>There might be a slight improvement but I haven't observed any. &nbsp;The difference might be that, because every node shares replicas with every other (with high probability), a single repair operation does the same work on the node it was called on, but the rest is spread out over the cluster, rather than just the RF nodes either side of the repairing node. &nbsp;This means the post-repair compaction work will take less time and the length of time a node is loaded for during repair is less.</div>


<div><br></div><div>However, the other benefits of vnodes are likely to be much more useful.</div><span class="HOEnZb"><font color="#888888"><div><br></div><div>Richard.</div></font></span></div></div></div>
</blockquote></div><br></div>
</blockquote></div><br></body></html>
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