I'd like to propose a new vote on having hdfs-630 committed to 0.21. The first vote on this topic, initiated 12/14/2009, was sunk by Tsz Wo (Nicholas), Sze suggested improvements. Those suggestions have since been folded into a new version of the hdfs-630 patch. Its this new version of the patch -- 0001-Fix-HDFS-630-0.21-svn-2.patch -- that I'd like us to vote on. For background on why we -- the hbase community -- think hdfs-630 important, see the notes below from the original call-to-vote.
I'm obviously +1. Thanks for you consideration, St.Ack P.S. Regards TRUNK, after chatting with Nicholas, TRUNK was cleaned of the previous versions of hdfs-630 and we'll likely apply 0001-Fix-HDFS-630-trunk-svn-4.patch, a version of 0001-Fix-HDFS-630-0.21-svn-2.patch that works for TRUNK that includes the Nicholas suggestions. On Mon, Dec 14, 2009 at 9:56 PM, stack <st...@duboce.net> wrote: > I'd like to propose a vote on having hdfs-630 committed to 0.21 (Its already > been committed to TRUNK). > > hdfs-630 adds having the dfsclient pass the namenode the name of datanodes > its determined dead because it got a failed connection when it tried to > contact it, etc. This is useful in the interval between datanode dying and > namenode timing out its lease. Without this fix, the namenode can often > give out the dead datanode as a host for a block. If the cluster is small, > less than 5 or 6 nodes, then its very likely namenode will give out the dead > datanode as a block host. > > Small clusters are common in hbase, especially when folks are starting out > or evaluating hbase. They'll start with three or four nodes carrying both > datanodes+hbase regionservers. They'll experiment killing one of the slaves > -- datanodes and regionserver -- and watch what happens. What follows is a > struggling dfsclient trying to create replicas where one of the datanodes > passed us by the namenode is dead. DFSClient will fail and then go back to > the namenode again, etc. (See > https://issues.apache.org/jira/browse/HBASE-1876 for more detailed > blow-by-blow). HBase operation will be held up during this time and > eventually a regionserver will shut itself down to protect itself against > dataloss if we can't successfully write HDFS. > > Thanks all, > St.Ack
