No. He's saying that one of the points of mmaping the data files is that the OS is free to only keep files that are actually used, in the page cache. Since this data is backed by an actual file swap is not involved.
On Thu, Aug 11, 2011 at 12:59 PM, Jason Baker <ja...@apture.com> wrote: > On Thu, Aug 11, 2011 at 6:14 AM, Edward Capriolo <edlinuxg...@gmail.com> > wrote: >> >> In many regards Cassandra automatically does the correct thing. Other then >> the costs of the bloom filters for the table size being in ram, if you never >> read or write to those sstables and you are not reusing the row key, the OS >> will page out those tables and they will not take any cache space. > > Forgive me if I'm being dense, but the wiki says that an instance shouldn't > be swapping at all[1]. I presently have swappiness turned down to 0. Are > you saying that there may be benefits to allowing some swap usage? > [1] http://wiki.apache.org/cassandra/MemtableThresholds?highlight=%28swap%29#Virtual_Memory_and_Swap -- Jonathan Ellis Project Chair, Apache Cassandra co-founder of DataStax, the source for professional Cassandra support http://www.datastax.com
