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From Jordan Zimmerman <jor...@jordanzimmerman.com>
Subject Re: How to restore a snapshot after an accidental ZKclenup
Date Mon, 22 Feb 2016 17:43:15 GMT
Be careful when restoring that you don’t go “back in time”. ZooKeeper can be used as
a datastore (bad idea) and a coordinator. If the transactions files you are restoring contain
paths that are involved in leader elections, etc. insanity can ensue.

> On Feb 22, 2016, at 9:05 AM, vikrant singh <vikrant.thakur@gmail.com> wrote:
> 
> I think you need not to worry about the leader election and who was the
> previous leader. Quorum should be able to handle it when it comes up.
> Neither you need to validate who becomes new leader.
> 
> Before you delete any files, please make sure you keep the back up so if
> your experiment fails you do not end up with no files to try again.
> 
> That said.. once all dat is backed up I would go and delete all the
> snapshot.* and log.*  except latest one. In your case I will leave
> snapshot.d0002bf88
> in the data folder. Please note the number at the end of file.. it is the
> transaction number after which this snap shout was created. On each of your
> ZK server you will have a file for which this number will be in the same
> range. Keep those file on the server.
> 
> I do not think you need to initialize any data manually.. once snapshot
> files are there in place you can start the  server and most likely it will
> come up.
> 
> All the best.
> 
> 
> 
> 
> 
> On Mon, Feb 22, 2016 at 7:08 AM, AALISHE <aalishe@gmail.com> wrote:
> 
>> Hi Vikrant/All,
>> 
>> I have some thought about the steps to share:
>> 
>> 
>> 1- Since this is a 3 node cluster ....  I must Identify which one is  the
>> (leader ZK node)
>> 2- Stop ZK from cloudera manager
>> 3- Go to snapshot folder (on the leader) and take a backup a side
>> 4- delete the files (snapshot + log) with the newest date stamp?  (on all 3
>> nodes)
>> 5-  Start ZK and make sure the previous leader is the current leader ?   or
>> maybe I should initialize ZK data ?
>> 
>> 
>> 
>> Can anyone take a look please and confirm/correct the above steps.
>> 
>> 
>> cheers!
>> 
>> On Mon, Feb 22, 2016 at 4:31 PM, vikrant singh <vikrant.thakur@gmail.com>
>> wrote:
>> 
>>> I have not tried it, but as I understand following should be the steps to
>>> follow.
>>> Step1 - back up these snapshot files
>>> Step2 - choose the snapshot files from which you want to recover.
>>> Step3 - remove all other files from data dir
>>> Step4 - Start server
>>> 
>>> On Mon, Feb 22, 2016 at 2:04 AM, AALISHE <aalishe@gmail.com> wrote:
>>> 
>>>> Anything anyone please?
>>>> On Feb 21, 2016 5:51 PM, "AALISHE" <aalishe@gmail.com> wrote:
>>>> 
>>>>> 
>>>>>> thanks Ted,
>>>>> 
>>>>> 
>>>>> 
>>>>> this is the link   http://pastebin.com/CgGi45EN
>>>>> 
>>>>> 
>>>>> cheers!
>>>>> 
>>>> 
>>> 
>> 


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