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Flume >> mail # user >> In flume-ng is there any advantages of 2-tier topology in  a cluster of  30-40 nodes?

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Re: In flume-ng is there any advantages of 2-tier topology in  a cluster of  30-40 nodes?

Thanks  Alexander for the reply.
I have added my thoughts in line.

On 01/30/2013 11:56 AM, Alexander Alten-Lorenz wrote:
> Hi,
> If the agents (Tier 1) have access to HDFS, each single client can put data into HDFS. But this doesn't make really sense, instead you want different files from different hosts in a structured view (maybe per host a directory, the contents inside split into buckets).
-- But if number of clients are lesser (say 30-40) why doesn't it make
sense to write directly?
Because ultimately purpose is to deliver the source data to HDFS
directly. (say in a single HDFS directory).
> When you implement a Tier 2 (maybe 2 or more servers who has access to HDFS), you can have more features like loadbalancing, HA and mirrored sinks, as example (one sink put the data into HDFS, the other sink into a other system for backup maybe). For stability and reliability a Tier 2 architecture is recommend. And made some things easier ;)
-- I didnt get the point how we get HA and load balancing using 2
tiers.  e.g.
1. If HDFS goes down then both in 1 tier case and 2 tier
case channel will grow until its maximum size.
2. If in 1-tier scenario one node goes down then its data wont reach HDFS.
Similarly in 2 tier scenario : if a node from 1st tier goes down then
its data
wont reach HDFS.

Could you please elaborate if I am missing something?
> Cheers,
>   Alex
> On Jan 30, 2013, at 7:05 AM, Jagadish Bihani <[EMAIL PROTECTED]> wrote:
>> Hi
>> In our scenario there are around 30 machines from which we want to put data into HDFS.
>> Now the approach we thought of initially was:
>> 1. First tier  : Agent which collect data from source then pass it to avro sink.
>> 2. Second tier:  Lets call those agents 'collectors' which collect data from First tier agents and then dump it to HDFS.
>> (Second tier agents are fewer in number say 4:1)
>> Instead of above topology if I simply use HDFS sink in first tier agents. It can serve the purpose.
>> And also number of nodes are lesser (say 30) that won't hurt HDFS namenode too much compared
>> to if number of nodes were say 1000.
>> But apart from that I don't say any advantage of adding the 2nd tier.
>> Is there any advantage I am missing in terms of failover, HDFS performance or any other parameter?
>> Regards,
>> Jagadish
> --
> Alexander Alten-Lorenz
> http://mapredit.blogspot.com
> German Hadoop LinkedIn Group: http://goo.gl/N8pCF