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From Ted Dunning <ted.dunn...@gmail.com>
Subject Re: Changing hosts
Date Wed, 11 May 2011 23:57:06 GMT
Alex,

I think that this process does a slightly different thing.  Your process is
good for cloning a cluster, but it doesn't address the problem of
transitioning a working cluster.  My process never has two clusters with the
same data so all transactions will always be applied to a single notional
version of the data.

The reason that this is important is a part of the process that neither of
us mentioned.  That is how to transition the clients.  My assumption is that
before the transition, all clients would re-open their ZK connection with
all 6 nodes in the list of servers.  Once this is done, my process will lead
the clients through the transition in a way that all updates will be visible
to all clients.  At the end, the clients should (eventually) trim their list
of servers to the shorter list of new servers.

With a cluster clone operation, there will be moments when some clients
connect to one cluster and some connect to the other.  That makes it hard to
understand how this will work well.

The OP can probably clarify which task they really wanted to accomplish.



On Wed, May 11, 2011 at 4:49 PM, Alexander Shraer <shralex@yahoo-inc.com>wrote:

> Hi Ted,
>
> There's a simpler way that works. Suppose that the original servers are A,
> B and C, and the new ones
> are D, E, F. Configure D, E and F to be in the configuration A, B, C, D, E,
> F and start them. Don't do any changes to
> A, B and C. After D, E and F synch with the leader (or at least 2 of them
> do), turn them off, change their config files to D, E, F and bring them up
> again.
>
> Alex
>
>
>
>
> > -----Original Message-----
> > From: Ted Dunning [mailto:ted.dunning@gmail.com]
> > Sent: Tuesday, May 10, 2011 8:39 AM
> > To: user@zookeeper.apache.org; Murali Krishna. P
> > Cc: zookeeper-user@hadoop.apache.org
> > Subject: Re: Changing hosts
> >
> > Step 1:  configure two of the new hosts to be part of a 5 node cluster
> > containing all of the
> > original nodes.
> >
> > Step 2:  reconfigure each of the original 3 nodes to be part of the the
> > 5
> > node cluster.
> >
> > Step 3: bounce each of the originals and start the two new servers.
> >
> > Step 4: configure the 6th server (previously untouched) to be part of a
> > three node cluster
> > containing only the 3 new nodes.
> >
> > Step 5: reconfigure servers 4 and 5.
> >
> > Step 6: bounce servers 4 and 5 and start server 6.
> >
> > Done.
> >
> > (wait for somebody else to critique this procedure before proceeding
> > with
> > it)
> >
> > On Tue, May 10, 2011 at 7:54 AM, Murali Krishna. P
> > <muralikpbhat@yahoo.com>wrote:
> >
> > > Hi,
> > >      I have a zookeeper cluster (3.2.2) with 3 hosts. I need to
> > replace all
> > > the 3 hosts with different machines. What is the best way to achieve
> > this
> > > without any data loss? I can shutdown my clients during this
> > operation.
> > >
> > >
> > >
> > > Thanks,
> > > Murali Krishna
>

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