Hi, all. I have a question about "batch" commit log sync behavior with C* version 2.2.8.
Here's what I have done: * set commitlog_sync to the "batch" mode as follows: > commitlog_sync: batch > commitlog_sync_batch_window_in_ms: 10000 * ran a script which inserts the data to a table * prepared a disk dedicated to store the commit logs According to the DataStax document, I expected that fsync is done once in a batch window (one fsync per 10sec in this case) and writes issued within this batch window are blocked until fsync is completed. In my experiment, however, it seems that the write requests returned almost immediately (within 300~400 ms). Am I misunderstanding something? If so, can someone give me any advices as to the reason why C* behaves like this? I referred to this document: https://docs.datastax.com/en/cassandra/2.2/cassandra/configuration/configCassandra_yaml.html#configCassandra_yaml__PerformanceTuningProps Regards, Satoshi
