Are you swapping? http://spyced.blogspot.com/2010/01/linux-performance-basics.html
otherwise there's something wrong w/ your vm (?), disk i/o doesn't block incoming writes in cassandra On Thu, Feb 25, 2010 at 8:49 AM, Boris Shulman <shulm...@gmail.com> wrote: > I don't think it is gc related issue. There is no correlation between > gc times and the freeze times. More over I don't see any gc activity > that lasts for omre than o.03 sec. But there is a correlation between > disk flushing operations. I've noticed that the system freezes each > time when my commit log reaches 1.1G. I have 1024M memtable size so I > assume this is when the data flushing occurs. > > > > On Thu, Feb 25, 2010 at 4:13 PM, Jonathan Ellis <jbel...@gmail.com> wrote: >> Then you should check GC timing with -Xverbose:gc option (see: >> http://wiki.apache.org/cassandra/RunningCassandra for how to modify >> jvm options) for a correlation. >> >> On Thu, Feb 25, 2010 at 8:09 AM, Boris Shulman <shulm...@gmail.com> wrote: >>> In these tests I perform only write operations, no reads. >>> >>> On Thu, Feb 25, 2010 at 4:07 PM, Jonathan Ellis <jbel...@gmail.com> wrote: >>>> The only kind of "freeze" that makes sense there is your reads are i/o >>>> bound and the extra disk activity is killing you. In that case the >>>> fix is to add more RAM, or give less to the JVM so the OS can use more >>>> for buffer cache. >>>> >>>> On Thu, Feb 25, 2010 at 8:01 AM, Boris Shulman <shulm...@gmail.com> wrote: >>>>> In my case the cassandra node freezes while memtable flush operation >>>>> is performed or compactation operation is performed. How can I >>>>> optimize the cassandra configuration in order to avoid this behavior? >>>>> I've tried both using large memtable size (1G) and small (128M) but in >>>>> every case I have some sort of freezes when the data is flushed to the >>>>> disk. >>>>> >>>>> Please advice. >>>>> >>>> >>> >> >
