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From Jordan Zimmerman <jor...@jordanzimmerman.com>
Subject Re: zk config 3.4.6
Date Tue, 08 Dec 2015 15:04:23 GMT
This is hard to answer categorically - hopefully others will give their views. For me: I’d
take down ABC, move the data files to D and then bring DEF up. Your down time, if done correctly
would be minimal and you’d only suffer 1 outage. In any other scenario you’d suffer multiple
outages, though of shorter duration.

-JZ

> On Dec 7, 2015, at 6:42 PM, elastic search <elastic.l.k@gmail.com> wrote:
> 
> Thanks much for posting that link.
> 
> We have a read mostly zk setup . Considering that how should i proceed with
> the migration.
> say from ABC to DEF
> 1. Add  host D  to the server list  [ ABCD ]
> 2. Restart
> 3. Remove A  [ BCD ]
> 4. Restart
> Till ABC gets replaced with DEF
> 
> Alternatively
> Set up DEF as a seperate cluster of its own
> Set up cnames that point  z1 ,z2 ,z3 to  A and D , B and E, and C and F
> respectively
> Add them to the zk client library
> Restart the client to pick up the cname
> At the point of release Remove cname entry to multiple hostnames and
> restart of clients.
> 
> Any other ideas ?
> 
> 
> On Mon, Dec 7, 2015 at 12:50 PM, Jordan Zimmerman <
> jordan@jordanzimmerman.com> wrote:
> 
>> My personal advice is to config the ensemble as you want it and just deal
>> with the down time. Rolling restarts can get messy. See here:
>> http://zookeeper-user.578899.n2.nabble.com/Rolling-config-change-considered-harmful-td7578761.html
>> 
>> 
>> 
>>> On Dec 7, 2015, at 3:46 PM, elastic search <elastic.l.k@gmail.com>
>> wrote:
>>> 
>>> So i was wondering what approach would be the desirable in terms of
>>> downtime for the manual reconfiguration
>>> Add all the 6 servers to the config . Bring up the 6 node Zk ensemble
>>> Once done remove the 3 old servers from all the config
>>> Restart followers
>>> Restart leader
>>> 
>>> I think a rolling restart would not work here correct ? I would need to
>>> bring down the whole ensemble and then start up with the 3 new nodes
>>> 
>>> On Mon, Dec 7, 2015 at 8:32 AM, Jordan Zimmerman <
>> jordan@jordanzimmerman.com
>>>> wrote:
>>> 
>>>> It’s not possible. Prior to 3.5.x config changes require instance
>>>> restarts. Once you restart the leader instance the ensemble will be
>>>> unavailable for a short period of time until a new election.
>>>> 
>>>> -Jordan
>>>> 
>>>>> On Dec 7, 2015, at 11:31 AM, elastic search <elastic.l.k@gmail.com>
>>>> wrote:
>>>>> 
>>>>> In zookeeper 3.4.6 how do i add and remove servers in zoo.cfg without
>>>>> affecting the cluster availability.
>>>>> 
>>>>> For example
>>>>> server.1=zoo1:2888:3888
>>>>> server.2=zoo2:2888:3888
>>>>> server.3=zoo3:2888:3888
>>>>> 
>>>>> Step 1  : Add 4th server in config
>>>>> server.1=zoo1:2888:3888
>>>>> server.2=zoo2:2888:3888
>>>>> server.3=zoo3:2888:3888
>>>>> server.4=zoo3:2888:3888
>>>>> 
>>>>> Step 2  : Remove 1st server in config
>>>>> server.2=zoo2:2888:3888
>>>>> server.3=zoo3:2888:3888
>>>>> server.4=zoo3:2888:3888
>>>>> 
>>>>> Up until the old servers have been replaced
>>>>> server.4=zoo2:2888:3888
>>>>> server.5=zoo3:2888:3888
>>>>> server.6=zoo3:2888:3888
>>>>> 
>>>>> As soon as the config change the servers become unusable . Please
>> suggest
>>>> 
>>>> 
>> 
>> 


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