Hi Gokul, You're correct that all of the stable released versions of Hadoop have a buggy implemention of append, and thus dfs.support.append is disabled in 0.20.
The new implementation of append has been tracked in HDFS-265 and is now complete in trunk - just a few more tests are being done on it at this point. Major props to the team at Yahoo for the work here! We'll have to wait some time before this new implementation is available in an Apache release - see the ongoing release thread on -general for more information on the timeline. Regarding ports of append into an 0.20 branch, we will be working on adding just hflush() functionality to our distribution (CDH) in CDH3, for the benefit of HBase. This distribution should be available within the next couple of months. The patches to track are HDFS-200, HDFS-142, and a number of other bug fixes on top of those. Please get in touch with me off list if you're interested in testing development builds with this functionality before it is generally available. Thanks -Todd On Mon, Mar 29, 2010 at 9:01 PM, Gokulakannan M <gok...@huawei.com> wrote: > Hi, > > I am new to hadoop. The following questions popped up in my mind > and I couldn't get answers from web. > > > > I found that in hdfs-default.xml, the property > "dfs.support.append" has been set to false by default with the description > > > > "Does HDFS allow appends to files? This is currently set to > false because there are bugs in the "append code" and is not supported in > any production cluster" > > > > So, is there a way to resolve this issue? any existing > patches(like HADOOP-1700 > < > http://issues.apache.org/jira/browse/HADOOP-1700?page=com.atlassian.jira.pl > ugin.system.issuetabpanels%3Aall-tabpanel> ) will solve the problem of > hadoop-append to be stable? > > > > From HADOOP-1700 > < > http://issues.apache.org/jira/browse/HADOOP-1700?page=com.atlassian.jira.pl > ugin.system.issuetabpanels%3Aall-tabpanel> , I can see that this feature > has been enabled and updated in trunk. But why it is not enabled in the > stable Hadoop release? > > > > Thanks, > > Gokul > > > > -- Todd Lipcon Software Engineer, Cloudera
