I mentioned during my Cassandra.yaml presentation at the summit that I never saw anyone use these settings. Things off by default are typically not highly not covered well by tests. It sounds like it is not working. Quick suggestion: go back in time maybe to a version like 1.2.X or 0.7 and see if it behaves like the yaml suggests it should.
On Thu, Oct 27, 2016 at 11:48 PM, Hiroyuki Yamada <mogwa...@gmail.com> wrote: > Hello Satoshi and the community, > > I am also using commitlog_sync for durability, but I have never > modified commitlog_sync_batch_window_in_ms parameter yet, > so I wondered if it is working or not. > > As Satoshi said, I also changed commitlog_sync_batch_window_in_ms (to > 10000) and restarted C* and > issued some INSERT command. > But, it actually returned immediately right after issuing. > > So, it seems like the parameter is not working correctly. > Are we missing something ? > > Thanks, > Hiro > > On Thu, Oct 27, 2016 at 5:58 PM, Satoshi Hikida <sahik...@gmail.com> > wrote: > > 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 > > >
