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Date: Sun, 28 Nov 2010 12:11:53 -0500
Message-ID: <AANLkTinLkiCzy1T1TzcshpDxYzv3Eq1E6eaijUeUTaVz@mail.gmail.com>
Subject: Re: Taking down a node in a 3-node cluster, RF=2
From: Jake Luciani <jakers@gmail.com>
To: user@cassandra.apache.org
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If you read/write data with quorum then you can safely take a node down in
this scenario.  Subsequent writes will use hinted handoff to be passed to
the node when it comes back up.

More info is here: http://wiki.apache.org/cassandra/HintedHandoff

Does that answer your question?

-Jake


On Sun, Nov 28, 2010 at 9:42 AM, Ran Tavory <rantav@gmail.com> wrote:

> to me it makes sense that if hinted handoff is off then cassandra cannot
> satisfy 2 out of every 3rd writes writes when one of the nodes is down since
> this node is the designated node of 2/3 writes.
> But I don't remember reading this somewhere. Does hinted handoff affect
> David's situation?
> (David, did you disable HH in your storage-config?
> <HintedHandoffEnabled>false</HintedHandoffEnabled>)
>
>
> On Sun, Nov 28, 2010 at 4:32 PM, David Boxenhorn <david@lookin2.com>wrote:
>
>> For the vast majority of my data usage eventual consistency is fine (i.e.
>> CL=ONE) but I have a small amount of critical data for which I read and
>> write using CL=QUORUM.
>>
>> If I have a cluster with 3 nodes and RF=2, and CL=QUORUM does that mean
>> that a value can be read from or written to any 2 nodes, or does it have to
>> be the particular 2 nodes that store the data? If it is the particular 2
>> nodes that store the data, that means that I can't even take down one node,
>> since it will be the mandatory 2nd node for 1/3 of my data...
>>
>
>
>
> --
> /Ran
>
>

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If you read/write data with quorum then you can safely take a node down in =
this scenario. =A0Subsequent writes will use hinted handoff to be passed to=
 the node when it comes back up.=A0<div><br></div><div>More info is here:=
=A0<a href=3D"http://wiki.apache.org/cassandra/HintedHandoff">http://wiki.a=
pache.org/cassandra/HintedHandoff</a><br>
<div><br></div><div>Does that answer your question?</div><div><br></div><di=
v>-Jake</div><div><br></div><div><br><div class=3D"gmail_quote">On Sun, Nov=
 28, 2010 at 9:42 AM, Ran Tavory <span dir=3D"ltr">&lt;<a href=3D"mailto:ra=
ntav@gmail.com">rantav@gmail.com</a>&gt;</span> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex;"><div dir=3D"ltr">to me it makes sense that =
if hinted handoff is off then cassandra cannot satisfy 2 out of every 3rd w=
rites writes when one of the nodes is down since this node is the designate=
d node of 2/3 writes.=A0<div>
But I don&#39;t remember reading this somewhere. Does hinted handoff affect=
 David&#39;s situation?</div>

<div>(David, did you disable HH in your storage-config? &lt;HintedHandoffEn=
abled&gt;false&lt;/HintedHandoffEnabled&gt;)<div class=3D"im"><br><br><div =
class=3D"gmail_quote">On Sun, Nov 28, 2010 at 4:32 PM, David Boxenhorn <spa=
n dir=3D"ltr">&lt;<a href=3D"mailto:david@lookin2.com" target=3D"_blank">da=
vid@lookin2.com</a>&gt;</span> wrote:<br>


<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex"><div dir=3D"ltr">For the vast majority of my=
 data usage eventual consistency is fine (i.e. CL=3DONE) but I have a small=
 amount of critical data for which I read and write using CL=3DQUORUM. <br>


<br>If I have a cluster with 3 nodes and RF=3D2, and CL=3DQUORUM does that =
mean that a value can be read from or written to any 2 nodes,=20
or does it have to be the particular 2 nodes that store the data? If it=20
is the particular 2 nodes that store the data, that means that I can&#39;t =
even take=20
down one node, since it will be the mandatory 2nd node for 1/3 of my=20
data... <br></div>
</blockquote></div><br><br clear=3D"all"><br></div>-- <br><div dir=3D"ltr">=
<font color=3D"#999999">/Ran</font></div><br>
</div></div>
</blockquote></div><br></div></div>

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