Make standard IO the default
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Key: CASSANDRA-1214
URL: https://issues.apache.org/jira/browse/CASSANDRA-1214
Project: Cassandra
Issue Type: Bug
Affects Versions: 0.7
Reporter: James Golick
The way mmap()'d IO is handled in cassandra is dangerous. It allocates
potentially massive buffers without any care for bounding the total size of the
program's buffers. As the node's dataset grows, this *will* lead to swapping
and instability.
This is a dangerous and wrong default for a couple of reasons.
1) People are likely to test cassandra with the default settings. This issue is
insidious because it only appears when you have sufficient data in a certain
node, there is absolutely no way to control it, and it doesn't at all respect
the memory limits that you give to the JVM.
That can all be ascertained by reading the code, and people should certainly do
their homework, but nevertheless, cassandra should ship with sane defaults that
don't break down when you cross some magic unknown threshold.
2) It's deceptive. Unless you are extremely careful with capacity planning, you
will get bit by this. Most people won't really be able to use this in
production, so why get them excited about performance that they can't actually
have?
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