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From Jonathan Gray <jg...@facebook.com>
Subject RE: zookeeper & HBase
Date Thu, 08 Jul 2010 23:24:55 GMT
ZK is sensitive to IO starvation which is why it is recommended to keep it on a separate node
or separate disk.  In most cases, giving ZK its own disk is sufficient and dedicated node(s)
are unnecessary.

On smallish clusters like 10 nodes, I would recommend starting with just 1 ZK node co-located
with your NameNode and HMaster, but with a dedicated disk just for ZK.  Since the NN is a
SPOF, having one ZK doesn't really lower your fault tolerance, except that it may be on a
non-raided disk.  I encourage RAID usage for NN and ZK.  JBOD for DN/RS.


> -----Original Message-----
> From: vramanathan00@aol.com [mailto:vramanathan00@aol.com]
> Sent: Thursday, July 08, 2010 4:20 PM
> To: user@hbase.apache.org
> Subject: zookeeper & HBase
>  I'm trying to have our deployment layout..I read one of the
> articles/FAQ (probably JG's)...that it's better to
> have zookeeper on separate cluster/separate sets of machine..I'm
> assuming that is the right approach..
> All our transactions are HBase (inserts, mapreduce-table as input,
> another table as output, other queries,..)
> Based on other thread on locality..RegionServer & Datanode i'll put on
> same hosts..
> If these boxes have enough capacity, do we need to put zookeeper on
> separate cluster?
> If it is on a separate cluster, my understanding is zookeper has much
> smaller memory footprint compared
> to HRegionServer/Datanodes..& it shld need that much CPU as
> well..correct?
> Is there any suggested guidance on number of zookeeper vs number of
> regionservers?..looking for some ratio..say 10 node cluster..
> how many zookeeper..?
> Please ignore responding to this ..if this is outside the etiquette
> thanks
> venkatesh

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