I presplit the table. The regionservers have gone down on occassion but have been up for a while (weeks). How could that result in having no regions on one node?
On Aug 1, 2012, at 11:39 PM, Adrien Mogenet <[email protected]> wrote: > Did you pre split your table or did you let balancer assign regions to > regionservers for you ? > > Did your regionserver(s) fail ? > > On Thu, Aug 2, 2012 at 8:31 AM, Bryan Keller <[email protected]> wrote: > >> I have an 8 node cluster and a table that is pretty well balanced with on >> average 36 regions/node. When I run a mapreduce job on the cluster against >> this table, the data locality of the mappers is poor, e.g 100 rack local >> mappers and only 188 data local mappers. I would expect nearly all of the >> mappers to be data local. DNS appears to be fine, i.e. the hostname in the >> splits is the same as the hostnames in the task attempts. >> >> The performance of the rack local mappers is poor and causes overall scan >> performance to suffer. >> >> The table isn't new and from what I understand, HDFS replication will >> eventually keep region data blocks local to the regionserver. Are there >> other reasons for data locality to be poor and any way to fix it? >> >> > > > -- > Adrien Mogenet > 06.59.16.64.22 > http://www.mogenet.me
