Thanks for the confirmation this is NOT the way to go. I will stick with 4 disks raid 0 with a single data directory.
On Mon, Aug 23, 2010 at 9:24 PM, Rob Coli <rc...@digg.com> wrote: > On 8/22/10 12:00 AM, Wayne wrote: > >> Due to compaction being so expensive in terms of disk resources, does it >> make more sense to have 2 data volumes instead of one? We have 4 data >> disks in raid 0, would this make more sense to be 2 x 2 disks in raid 0? >> That way the reader and writer I assume would always be a different set >> of spindles? >> > > Cassandra supports multiple data directories via specifying multiple > DataFileDirectory items in the DataFileDirectories block. Unfortunately due > to the way that compaction currently works, this often results in one or the > other drive being much hotter than the other and lots of inter-disk > shuffling of data. > > https://issues.apache.org/jira/browse/CASSANDRA-897 > > Is a JIRA which refers to these issues. I am not aware of anyone who has > successfully improved their overall performance via multiple data > directories. I am, however, aware of people who have encountered negative > consequences as a result of doing so. As such, I do not recommend it. > > =Rob > >
