Fixed Issues in HDFS

Review the list of HDFS issues that are resolved in Cloudera Runtime 7.2.6.

CDPD-6100
This improvement makes HDFS NameNode leave safemode immediately if all blocks have reported in, reducing the cluster startup time.
CDPD-2946: Slow reading and writing of erasure-coded files
The ISA-L library is not packaged with HDFS as a result of which HDFS erasure coding falls back to the Java implementation which is much slower than the native Hadoop implementation. This slows down the reading and writing of erasure-coded files.
OPSAPS-43909: Execution filter is not applied to Delete Policy.
Execution filter is now applied to Delete Policy also. This issue is now resolved.