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Date: Thu, 12 May 2011 09:54:32 -0400
Message-ID: <BANLkTikrpM-RTcsoPsWGKAAcAN-htZsFAw@mail.gmail.com>
Subject: Re: Changing hosts
From: Vishal Kher <vishalmlst@gmail.com>
To: user@zookeeper.apache.org, "Murali Krishna. P" <muralikpbhat@yahoo.com>
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Hi,

Since you can stop clients, another way to achieve what Alex suggested is
to:

1. stop clients
2. stop all current zk servers (a_i)
3. scp -r /etc/zookeeper/ from a_i to b_i
4. scp -r /var/zookeeper/ from a_i to b_i
5. On all b_i, edit /etc/zookeeper/zoo.cfg to reflect the correct IP
addresses
5 start all b_i

This is assuming that stopping ZK server is ok in our environment.

-Vishal

On Thu, May 12, 2011 at 2:07 AM, Murali Krishna. P
<muralikpbhat@yahoo.com>wrote:

> Thanks for the responses,
>      I have the luxury of stopping the clients during the operations. So, I
> would go with the second approach of cloning.
>
>
> Thanks,
> Murali Krishna
>
>
> ________________________________
> From: Ted Dunning <ted.dunning@gmail.com>
> To: Alexander Shraer <shralex@yahoo-inc.com>
> Cc: "user@zookeeper.apache.org" <user@zookeeper.apache.org>; Murali
> Krishna. P <muralikpbhat@yahoo.com>; "zookeeper-user@hadoop.apache.org" <
> zookeeper-user@hadoop.apache.org>
> Sent: Thursday, 12 May 2011 5:27 AM
> Subject: Re: Changing hosts
>
>
> 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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