[ http://issues.apache.org/jira/browse/HADOOP-657?page=comments#action_12450138 ] Arun C Murthy commented on HADOOP-657: --------------------------------------
It should be very useful to include the 'unallocated disk space' in the global and per-host jsps so as to provide an easy way for operator to diagnose if and when tasks can't be allocated due to lack of diskspace... I think it should be a part of this same bug. > Free temporary space should be modelled better > ---------------------------------------------- > > Key: HADOOP-657 > URL: http://issues.apache.org/jira/browse/HADOOP-657 > Project: Hadoop > Issue Type: Improvement > Components: mapred > Affects Versions: 0.7.2 > Reporter: Owen O'Malley > Assigned To: Arun C Murthy > > Currently, there is a configurable size that must be free for a task tracker > to accept a new task. However, that isn't a very good model of what the task > is likely to take. I'd like to propose: > Map tasks: totalInputSize * conf.getFloat("map.output.growth.factor", 1.0) / > numMaps > Reduce tasks: totalInputSize * 2 * conf.getFloat("map.output.growth.factor", > 1.0) / numReduces > where totalInputSize is the size of all the maps inputs for the given job. > To start a new task, > newTaskAllocation + (sum over running tasks of (1.0 - done) * allocation) > >= > free disk * conf.getFloat("mapred.max.scratch.allocation", 0.90); > So in English, we will model the expected sizes of tasks and only task tasks > that should leave us a 10% margin. With: > map.output.growth.factor -- the relative size of the transient data relative > to the map inputs > mapred.max.scratch.allocation -- the maximum amount of our disk we want to > allocate to tasks. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
