1 Append/Hflush/Read Design Hairong Kuang, Konstantin Shvachko, Nicholas Sze, Sanjay Radia, Robert Chansler Yahoo! HDFS team 08/06/2009 1. Design challenges With hflush, HDFS needs to make the last block of an unclosed file visible to readers. This presents two challenges: 1. Read consistency. At a given time different replicas of the last block may have different number of bytes. What read consis