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From Arun Ramakrishnan <aramakrish...@languageweaver.com>
Subject RE: zookeeper & HBase
Date Fri, 09 Jul 2010 00:38:22 GMT
Good to know ZK is IO intense. 
Since ZK does not require much disk space and is IO intense. Has anyone played with using
solid state drives for ZK.
We have a 20 node cluster. It would be feasible to have a 3 node ZK all configured with solid
state drives.


-----Original Message-----
From: Jonathan Gray [mailto:jgray@facebook.com] 
Sent: Thursday, July 08, 2010 4:25 PM
To: user@hbase.apache.org
Subject: RE: zookeeper & HBase

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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