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I'm using Cassandra 2.1 with 3 nodes, one of them is configured as seed. The cluster seems to be working fine, and read/query speed is nice. But writing speed is really bad. About 1000-2000 rows/sec. Considering I need to push a database with millions of rows, the time cost is inadmissible.

The rows have 4 primary keys.

I've tried with replication factor 1, which I though could speed it up considerably, with no results.

Is this the expected performance or am I probably doing something wrong? If so, what would be good ways to diagnose? Looking at CPU/memory usage in the nodes, they seem to be high on the CPU front and normal on memory (25%).

I don't think network is a problem because I've experienced this performance in a local setup with only one node too!

Thank you for your help! Any pointers are appreciated.

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  • 2 things to consider here - Hardware and code. What hardware are you using (including hard drives) and how are you loading the data? Are you using batch by chance? – MarcintheCloud Feb 15 '16 at 17:39
  • Hi there! I'm experiencing the same issue: http://stackoverflow.com/questions/35176363/cassandra-partition-size-and-performance Datastax guys say this might be because of slow I/O. I haven't checked the I/O yet however you might want to do this. Or to play around with the partition size (but in accordance with Datastax partition size shouldn't be a problem in case your hardware setup is okay). – bopcat Feb 16 '16 at 10:38

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