Hi Julien,

I hope I get this right :)

a repair will trigger a mayor compaction on your node which will take up a lot of CPU and IO performance. It needs to do this to build up the data structure that is used for the repair. After the compaction this is streamed to the different nodes in order to repair them.

If you trigger this on every node simultaneously you basically take the performance away from your cluster. I would expect cassandra still to function, just way slower then before. Triggering it node after node will leave your cluster with more resources to handle incoming requests.


On 25/11/13 15:12, Julien Campan wrote:

I'm working with Cassandra 1.2.2 and I have a question about nodetool cleanup.
In the documentation , it's writted " Wait for cleanup to complete on one node before doing the next"

I would like to know, why we can't perform a lot of cleanup in a same time ?