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From 史英杰 <shiyingjie1...@gmail.com>
Subject Re: What happened if one server involved in the process of data reading fail?
Date Fri, 21 May 2010 01:50:51 GMT
What inner mechanism does Cassandra adopt to get this kind of fault
tolerance?

2010/5/20 Simon Smith <simongsmith@gmail.com>

> On Thu, May 20, 2010 at 8:08 AM, 史英杰 <shiyingjie1983@gmail.com> wrote:
> > Hi, All,
> >     I am now learning the mechanism Cassandra adopts to get high
> > availability and fault tolerance.  As I know, we should connect to one
> > server of Cassandra first, then we can read or write data  through it, so
> if
> > the server which we connect to get down, what will happen? Should we have
> to
> > reconnect another server or will Cassandra control this situation?
>
>
> The approach we're taking is to put the software load-balancer haproxy
> in front of our cassandra cluster.  Use "mode tcp" within haproxy's
> config.  I notice that Tragedy (http://github.com/enki/tragedy/) also
> lets you put a list of servers into the connection call (we're going
> to put the list of haproxy load balancers here).
>
>
>
> > Another sutiation, if the server which is involved in the process of data
> reading
> > fail, what will Cassandra do?
>
>
> If you're using Thrift to connect, catch the exceptions that library
> throws if unable to connect and then try to connect again.   This is
> going to happen - if/when a node goes down it causes the entire
> cluster to hiccup a little, so if it is critical that any particular
> read transaction succeeds, you may need to sleep as much as 5 seconds
> (this is just my experience).
>
>
> >     Thanks a lot!
> >
> > Yingjie
>

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