This is not advisable in general, since non-mmap'd I/O is substantially slower.
The OP is correct that it is best to disable swap entirely, and second-best to enable JNA for mlockall. On Thu, Jul 28, 2011 at 7:05 AM, Adi <adi.pan...@gmail.com> wrote: >> Hi, >> >> >> >> We’ve started having problems with cassandra and memory swapping on linux >> which seems to be a fairly common issue (in our particular case after about >> a week all swap space will have been used up and we have to restart the >> process). >> >> >> >> It sounds like the general consensus is to just disable swap completely, >> but the recently released “Cassandra High Performance Cookbook” from Packt >> has instructions for “Stopping cassandra from using swap without disabling >> it system wide”. We’ve tried following the instructions but it refers to a >> “memory_locking_policy” variable in cassandra.yaml which throws an “unknown >> property” error on startup and I can’t find any reference to it in any of >> the cassandra docs. >> >> >> >> I’ve copied the summarised instructions below, does anyone know if this is >> something that ever worked or is there a different variable to set which >> does the same thing? > > If you are having trouble preventing the swapping the other parameter that > can help is disk_access_mode > We are using "mmap_index_only" and that has prevented swapping for now. > "auto" will try to use mmap for all disk access , > "mmap" will use mmap > "standard" will not use mmap > > Search for swapping on the users list and go through the email discussions > and jira issues related to swapping and that will give you an idea what can > work for you. > -Adi -- Jonathan Ellis Project Chair, Apache Cassandra co-founder of DataStax, the source for professional Cassandra support http://www.datastax.com
