Parag:
To answer your questions:
1) Default is just that, a default. I wouldn't advise raising it
though. The bigger it is the longer it takes to restart the node.
2) I think they juse use fsync. There is no queue. All files in
cassandra use java.nio buffers, but they need to be fsynced
periodically. Look at commitlog_sync parameters in cassandra.yaml file,
the comments there explain how it works. I believe the difference
between periodic and batch is just that -- if it is periodic, it will
fsync every 10 seconds, if it is batch it will fsync if there were any
changes within a time window.
On 2014-04-09 10:06:52 +0000, Parag Patel said:
1) Why is the default 4GB? Has anyone changed this? What are some
aspects to consider when determining the commitlog size?
2) If the commitlog is in periodic mode, there is a property to
set a time interval to flush the incoming mutations to disk. This
implies that there is a queue inside Cassandra to hold this data in
memory until it is flushed.
a. Is there a name for this queue?
b. Is there a limit for this queue?
c. Are there any tuning parameters for this queue?
Thanks,
Parag
--
Regards,
Oleg Dulin
http://www.olegdulin.com
