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From David Boxenhorn <da...@lookin2.com>
Subject Write assurance in Cassandra
Date Sun, 04 Jul 2010 07:34:20 GMT
As I understand it, when you write to Cassandra, you are assured that, if
successful, the new data has been written to a log file - so that if there
is a crash your data is safe. Is this correct?

If the above is correct, there is something going on that I don't
understand. Are the log files to which the data is first written the ones
that look like /var/lib/cassandra/commitlog/CommitLog-1277998453387.log ?
The reason I ask is that when I write a lot of data, nothing seems to change
in the commitlog directory for a long time, then at some point the log files
in this directory get updated. It looks to me like there's memory caching
involved, and the new data is not being immediately written to disk. What is
going on?

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