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From lars hofhansl <la...@apache.org>
Subject Re: HBase Thrift inserts bottlenecked somewhere -- but where?
Date Sat, 02 Mar 2013 03:42:57 GMT
What performance profile do you expect?
Where does it top out (i.e. how many ops/sec)?

Also note that each data item is replicated to three nodes (by HDFS). So in a 6 machine cluster
each machine would get 50% of the writes.
If you are looking for performance you really need a larger cluster to amortize this replication
cost across more machines.

The other issue to watch out for is whether your keys are generated such that a single regionserver
is hot spotted (you can look at the operation count on the master page).

-- Lars

 From: Dan Crosta <dan@magnetic.com>
To: "user@hbase.apache.org" <user@hbase.apache.org> 
Sent: Friday, March 1, 2013 4:17 AM
Subject: HBase Thrift inserts bottlenecked somewhere -- but where?
We are using a 6-node HBase cluster with a Thrift Server on each of the RegionServer nodes,
and trying to evaluate maximum write throughput for our use case (which involves many processes
sending mutateRowsTs commands). Somewhere between about 30 and 40 processes writing into the
system we cross the threshold where adding additional writers yields only very limited returns
to throughput, and I'm not sure why. We see that the CPU and Disk on the DataNode/RegionServer/ThriftServer
machines are not saturated, nor is the NIC in those machines. I'm a little unsure where to
look next.

A little more detail about our deployment:

* CDH 4.1.2
* DataNode/RegionServer/ThriftServer class: EC2 m1.xlarge
** RegionServer: 8GB heap
** ThriftServer: 1GB heap
** DataNode: 4GB heap
** EC2 ephemeral (i.e. local, not EBS) volumes used for HDFS

If there's any other information that I can provide, or any other configuration or system
settings I should look at, I'd appreciate the pointers.

- Dan
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