Hey Suraj, I would recommend turning on MSlab and using the following settings:
-XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=70 -XX:+CMSParallelRemarkEnabled On Mon, Jul 8, 2013 at 2:09 PM, Suraj Varma <[email protected]> wrote: > Hello: > We have an HBase cluster with region servers running on 8GB heap size with > a 0.6 block cache (it is a read heavy cluster, with bursty write traffic > via MR jobs). (version: hbase-0.94.6.1) > > During HBaseCon, while speaking to a few attendees, I heard some folks were > running region servers as high as 24GB and some others in the 16GB range. > > So - question: Are there any special GC recommendations (tuning parameters, > flags, etc) that folks who run at these large heaps can recommend while > moving up from an 8GB heap? i.e. for 16GB and for 24GB RS heaps ... ? > > I'm especially concerned about long pauses causing zk session timeouts and > consequent RS shutdowns. Our boxes do have a lot of RAM and we are > exploring how we can use more of it for the cluster while maintaining > overall stability. > > Also - if there are clusters running multiple region servers per host, I'd > be very interested to know what RS heap sizes those are being run at ... > and whether this was chosen as an alternative to running a single RS with > large heap. > > (I know I'll have to test the GC stuff out on my cluster and for my > workloads anyway ... but just trying to get a feel of what sort of tuning > options had to be used to have a stable HBase cluster with 16 or 24GB RS > heaps). > > Thanks in advance, > --Suraj > -- Kevin O'Dell Systems Engineer, Cloudera
