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From Karl Wright <daddy...@gmail.com>
Subject RE: Zookeeper in Apache ManifoldCF
Date Mon, 30 Jun 2014 17:50:11 GMT
Hi Lalit,

You can keep things really simple by having both active and passive mcf
instances run each as a single process, either under jetty or using the
combined war under tomcat.  If that is not acceptable, you would need two
sets of three zookeeper machines, one set for each instance.

Karl

Sent from my Windows Phone
------------------------------
From: lalit jangra
Sent: 6/30/2014 12:19 PM
To: user@manifoldcf.apache.org
Subject: Re: Zookeeper in Apache ManifoldCF

Thanks Karl & Graeme,

Let me elaborate my scenario and what i am trying to achieve.

I have two servers each running MCF 1.5.1 individually. But both of them
are backed by same PostGreSQL DB so both of MCF applications are pointing
to same DB at any point of time, without having their own dedicated DBs.
Next, primary/active DB instance is  backed up with periodical backups from
active to passive instance.

Only one DB instance will be active at any time, with other DB instance
acting as active standby. In case of breakdown of primary/active instance,
passive/secondary will take over and becomes primary/active instance
handling all DB transactions, thus making primary as new secondary DB
instance.

Similarly i have two solr 4.6 instances which act in active/passive mode
with periodic backup of active/primary to passive/secondary with active
standby and failover.

So my intention of clustering is high availability of system with failover
but i will not use both of MCF instances parallely or simultaneously.

Finally i am limited to having two instances only but as mentioned earlier,
we need at least three Zookeeper instances for a proper Zookeeper
clustering.

Is it still worthy to go and use Zookeeper or i can do simple clustering
where each of MCF node is clustered using same DB. Please suggest.

Thanks for help.

Regards.


On Fri, Jun 27, 2014 at 11:15 AM, Graeme Seaton <lists@graemes.com> wrote:

>  Hi Lalit,
>
> For production use, you will want to spin up your own ZK cluster using the
> instructions on the zookeeper site (as pointed out earlier at least 3 is
> recommended)....
>
> You then need to modify the properties.xml file in multiprocess-zk-example
> to point to the list of Zookeeper servers.  You also need to modify
> properties-global.xml with the appropriate global settings i.e. logging
> levels, Postgresql database etc. and then run setglobalproperties.sh to
> register the settings in ZK.
>
> To test that is working, set up a crawl and then tail the manifoldcf.log
> file on each of your nodes to check that they are all crawling in parallel.
>
> HTH,
>
> Graeme
>
>
> On 25/06/14 12:19, Karl Wright wrote:
>
>  Hi Lalit,
>
> Zookeeper does not use a database; it keeps its stuff in the local file
> system.  Each Zookeeper node has its own local data, and everything else is
> socket communication between them.
>
>  As for information: http://zookeeper.apache.org/
>
>  Karl
>
>
>
> On Wed, Jun 25, 2014 at 6:56 AM, lalit jangra <lalit.j.jangra@gmail.com>
> wrote:
>
>>  Thanks Karl,
>>
>> Apologies as i am not very familiar with Zookeeper and trying to figure
>> out on same.
>>
>> Is there any more documentation/pointers available for same as that would
>> be more helpful.
>>
>>  Also i have 2 tomcat servers in cluster, each having MCF 1.5.1 setup
>> and configured to point to same PostGreSQL DB & DB is backed up for
>> failover. From your inputs, it seems that we need to configure a separate
>> standalone Zookeeper server which will act as Master and both nodes in
>> cluster will need to work as slaves and talk to standalone Zookeeper master.
>>
>>  Also the Zookeeper server will have its own DB so either we can host it
>> separately or we can use same Postgres DB?
>>
>>  Regards.
>>
>>
>>
>> On Wed, Jun 25, 2014 at 11:33 AM, Karl Wright <daddywri@gmail.com> wrote:
>>
>>>   Hi Lalit,
>>>
>>>  1. zookeeper is already spun into MCF.  in fact you start a zookeeper
>>> instance when you run the mcf zookeeper example.  They recommend, though,
>>> that for failover you have 3 instances, etc.
>>>  2. Looks like the documentation is out of date and something old is
>>> left in there.
>>>  3. Zookeeper is a client/server kind of arrangement.  You need at least
>>> ONE zookeeper server, and each cluster member includes a zookeeper client,
>>> which is configured to talk with ALL the zookeeper server instances you
>>> have.
>>>  4.  There is ONE database instance; the instance may be supported by
>>> failover and redundant Postgresql, but it appears as one instance.  TO get
>>> failover from Postgres you need the Enterprise Edition, which costs money.
>>>
>>> Karl
>>>
>>>
>>>
>>>
>>> On Wed, Jun 25, 2014 at 4:47 AM, lalit jangra <lalit.j.jangra@gmail.com>
>>> wrote:
>>>
>>>>     Thanks Karl,
>>>>
>>>>  That was helpful.
>>>>
>>>>  I am setting clustered setup on Tomcats as i was following
>>>> instructions @
>>>> http://manifoldcf.apache.org/release/trunk/en_US/how-to-build-and-deploy.html#Simplified+multi-process+model+using+ZooKeeper-based+synchronization
>>>> and i need some suggestions here.
>>>>
>>>>  1. Do we need to download zookeeper and put it in
>>>> multiprocess-zk-example folder or it is already spun into MCF and we are
>>>> good to go?
>>>>  2. It says all jars under *processes *should be put into classpath
>>>> but i can not see any *processes *folder under MCF?
>>>>  3. Do we need to setup Zookeeper on both nodes or only at one node, i
>>>> assume we need to do on both nodes ?
>>>>  4. Do we also need to setup databases separately on both nodes again.
>>>> Also can we setup Zookeeper DB using same PostGreSQL or it will use its own
>>>> HSQL DB?
>>>>
>>>>  Finally how can i test that my Zookeeper is setp and ready to roll?
>>>>
>>>>  Thanks for your help.
>>>>
>>>> Regards.
>>>>
>>>>
>>>>  On Tue, Jun 24, 2014 at 1:56 PM, Karl Wright <daddywri@gmail.com>
>>>> wrote:
>>>>
>>>>>  Hi Lalit,
>>>>>  ZooKeeper is standard for cluster deployments these days.  See the
>>>>> multiprocess-zookeeper example for ideas about how to deploy it.  It's
also
>>>>> important to read the how-to-build-and-deploy page to understand the
>>>>> example.
>>>>>
>>>>> Thanks,
>>>>> Karl
>>>>>
>>>>>
>>>>>
>>>>> On Tue, Jun 24, 2014 at 8:04 AM, lalit jangra <
>>>>> lalit.j.jangra@gmail.com> wrote:
>>>>>
>>>>>>  Hi,
>>>>>>
>>>>>>  I am planning to use MCF in cluster mode. For same, i want to know
>>>>>> if Zookeeper is of any help here?
>>>>>>
>>>>>>  If yes, how can it be leveraged in distributed MCF servers?
>>>>>>
>>>>>> Regards,
>>>>>> Lalit Jangra.
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>  --
>>>> Regards,
>>>> Lalit Jangra.
>>>>
>>>
>>>
>>
>>
>>  --
>> Regards,
>> Lalit Jangra.
>>
>
>
>


-- 
Regards,
Lalit Jangra.

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