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From: Yiming Sun <yiming.sun@gmail.com>
Date: Sat, 10 Sep 2011 15:52:55 -0400
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 <CABxBLH_PQTcMVqNR_2v_h5Kh6rZ2w1m+5u=Tdbnd3YZgwbGB+g@mail.gmail.com>
Subject: Re: mysterious data disappearance - what happened?
To: user@cassandra.apache.org
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Hi Peter,

Good call! I went and checked the seed, and indeed it left unchanged when we
copied the config yaml file from the first node to the second node.  Thanks!

-- Y.

On Fri, Sep 9, 2011 at 7:47 PM, Peter Schuller
<peter.schuller@infidyne.com>wrote:

> > cluster name for both machines.  So in other words, if we want to launch
> two
> > separate instances of cassandra and keep them separate, we must make sure
> > each uses a different cluster name or else they will gang up into the
> same
> > cluster?  But how do they even discover each other?  Can someone
> enlighten
> > me please?  Thanks.
>
> It is highly recommended to use distinct cluster names, in particular
> because it can help avoid accidentally "merging" two independent
> clusters.
>
> As for how it happened: There is no magic discovery going on that
> would pick IP:s at random, but one could certainly e.g. accidentally
> configure the seed node on one to point to the other or some such.
>
> (1) does nodetool -h localhost ring show an unexpected node?
> (2) i'd suggest checking system.log on each node for the first
> appearance (if any) of the "unexpected" ip address and correlate (by
> time) with what happened on the other node (was it restarted at the
> time for example, potentially wth a bad conf?)
> (3) are these two single-instance cassandras that have never
> participated in another cluster?
>
> --
> / Peter Schuller (@scode on twitter)
>

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Hi Peter,<div><br></div><div>Good call! I went and checked the seed, and in=
deed it left unchanged when we copied the config yaml file from the first n=
ode to the second node. =A0Thanks!</div><div><br></div><div>-- Y.<br><br><d=
iv class=3D"gmail_quote">

On Fri, Sep 9, 2011 at 7:47 PM, Peter Schuller <span dir=3D"ltr">&lt;<a hre=
f=3D"mailto:peter.schuller@infidyne.com">peter.schuller@infidyne.com</a>&gt=
;</span> wrote:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 =
.8ex;border-left:1px #ccc solid;padding-left:1ex;">

<div class=3D"im">&gt; cluster name for both machines. =A0So in other words=
, if we want to launch two<br>
&gt; separate instances of cassandra and keep them separate, we must make s=
ure<br>
&gt; each uses a different cluster name or else they will gang up into the =
same<br>
&gt; cluster? =A0But how do they even discover each other? =A0Can someone e=
nlighten<br>
&gt; me please? =A0Thanks.<br>
<br>
</div>It is highly recommended to use distinct cluster names, in particular=
<br>
because it can help avoid accidentally &quot;merging&quot; two independent<=
br>
clusters.<br>
<br>
As for how it happened: There is no magic discovery going on that<br>
would pick IP:s at random, but one could certainly e.g. accidentally<br>
configure the seed node on one to point to the other or some such.<br>
<br>
(1) does nodetool -h localhost ring show an unexpected node?<br>
(2) i&#39;d suggest checking system.log on each node for the first<br>
appearance (if any) of the &quot;unexpected&quot; ip address and correlate =
(by<br>
time) with what happened on the other node (was it restarted at the<br>
time for example, potentially wth a bad conf?)<br>
(3) are these two single-instance cassandras that have never<br>
participated in another cluster?<br>
<font color=3D"#888888"><br>
--<br>
/ Peter Schuller (@scode on twitter)<br>
</font></blockquote></div><br></div>

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