Without knowing your exact configuration… The High CPU may be WAIT IOs, which would mean that you’re cpu is waiting for reads from the local disks.
What’s the ratio of cores (physical) to disks? What type of disks are you using? That’s going to be the most likely culprit. > On May 13, 2015, at 11:41 AM, rahul malviya <malviyarahul2...@gmail.com> > wrote: > > Yes. > > On Wed, May 13, 2015 at 9:40 AM, Ted Yu <yuzhih...@gmail.com> wrote: > >> Have you enabled short circuit read ? >> >> Cheers >> >> On Wed, May 13, 2015 at 9:37 AM, rahul malviya <malviyarahul2...@gmail.com >>> >> wrote: >> >>> Hi, >>> >>> I have recently started running MR on hbase snapshots but when the MR is >>> running there is pretty high CPU usage on datanodes and I start seeing IO >>> wait message in datanode logs and as soon I kill the MR on Snapshot >>> everything come back to normal. >>> >>> What could be causing this ? >>> >>> I am running cdh5.2.0 distribution. >>> >>> Thanks, >>> Rahul >>> >>
