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From Chris Goffinet>
Subject Re: what causes a cassandra to block and throw a null exception
Date Wed, 21 Jul 2010 04:03:40 GMT
Can you provide the output from `nodetool tpstats`.


On Jul 20, 2010, at 8:59 PM, Dathan Pattishall wrote:

> Type 'help' or '?' for help. Type 'quit' or 'exit' to quit.
> cassandra> connect cass01/9160
> cassandra> get TimeFrameClicks.Standard2['test_cassandra_alive']
> Exception null
> The data exists and I can grab the data after I restart all the nodes,
> but once the cluster runs for a few minutes I cannot grab this
> specific key or random other keys. It takes about  3 seconds until the
> Exception null message. My storage-conf.xml is very simple:
> <Keyspace Name="TimeFrameClicks">
>  <ColumnFamily Name="Standard2" CompareWith="UTF8Type" />
> ....
> Now my data is very small like 20 GB across 4 servers. Writes
> consistently remain fast, yet reads fail like crazy. I hope its
> something that I am doing wrong because
> nodetool cfstats
> says that the read latency for the keyspace and this specific column
> family is less then 0.3 ms which means that something is lying to me.
> To head off some questions:
> CPU utilization is very little.
> There is hardly any I/O on the box
> The servers are all the same class enterprise boxes
> There is 12 GB of ram per server
> Each Server uses a local RAID.
> Nothing in any of the system logs that indicates there any problem.
> Additionally is there a stat or series of stats that I can lookup to
> determine the health of read performance.

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