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From "Vazhenin, Maksim" <Maksim.Vazhe...@dell.com>
Subject RE: rolling upgrade with wiped disk
Date Fri, 21 Oct 2016 13:35:54 GMT
Thanks for reply, Flavio,

"You have to be careful when you do this. You may end up losing quorum on txns if you wipe
out the disk of a server prematurely."
What steps could be performed to not loose quorum? If quorum is lost what steps are to be
performed to fix it?
Is there a chance to loose data stored in zk in this scenario?
On node failure / node replacement it is inevitable to have disk wiped for one server (this
should be handled by zk as this will happen eventually on all systems running zk).
Does upgrading zk version on node with wiped disk adds a situation not supported by zk?

"On your step 4, you can tell that a server is ready once clients are able to connect to it
successfully."
Do you mean client should have only this server in the connection string, and once this client
get respond for any 'get' operation it means that it is safe to go ahead?

Thanks,
Maksim

-----Original Message-----
From: Flavio Junqueira [mailto:fpj@apache.org] 
Sent: Friday, October 21, 2016 3:59 PM
To: user@zookeeper.apache.org
Subject: Re: rolling upgrade with wiped disk

Hi Maksim,

You have to be careful when you do this. You may end up losing quorum on txns if you wipe
out the disk of a server prematurely.

On your step 4, you can tell that a server is ready once clients are able to connect to it
successfully.

Thanks,
-Flavio

> On 21 Oct 2016, at 09:11, Vazhenin, Maksim <Maksim.Vazhenin@dell.com> wrote:
> 
> Hi,
> 
> Is this a supported scenario for doing rolling upgrade of zookeeper (v3.4.5) to later
version (say v3.4.9):
> 
> 1. Shutdown server A (v3.4.5)
> 2. Wipe disk with zookeeper data on server A 3. Start server A with 
> new zk version (v3.4.9) 4. Wait till reconstruction complete on server 
> A (what is the indicator for completion?) 5. Go to server B and repeat 
> 1-4.
> 
> Thanks,
> Maksim


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