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From: Bo Finnerup Madsen <bo.gunder...@gmail.com>
Sent: Wednesday, April 20, 2016 9:38 AM
To: user@cassandra.apache.org
Subject: When are hints written?

Hi,

We have a small 5 node cluster of m4.xlarge clients that receives writes from 
~20 clients. The clients will write as fast as they can, and the whole process 
is limited by the write performance of the cassandra cluster.
After we have tweaked our schema to avoid large partitions, the load is going 
ok and we don't see any warnings or errors in the cassandra logs. But we do see 
quite a lot of hint handoff activity. During the load, the cassandra nodes are 
quite loaded, with linux reporting a load as high as 20.

I have read the available documentation on how hints works, and to my 
understanding hints should only be written if a node is down. But as far as I 
can see, none of the nodes are marked as down during the load. So I suspect I 
am missing something :)
We have configured the servers with write_request_timeout_in_ms: 120000 and the 
clients with a timeout of 130000, but still get hints stored.

In our case, I would like for the cluster to wait for the write to be persisted 
on the relevant nodes before returning an ok to the client. But I don't know 
which knobs to turn to accomplish this? or if it is even possible :)

We are running cassandra 3.0.3, with 8Gb heap and a replication factor of 3.

Thank you in advance!

Yours sincerely,
  Bo Madsen

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