Optimize mountable HDFS

You can consider certain recommendations to optimize the mountable HDFS.

Cloudera recommends that you use the -obig_writes option on kernels later than 2.6.26. This option allows for better performance of writes.
By default, the package installation creates the /etc/default/hadoop-fuse file with a maximum heap size of 128 MB. You might need to change the JVM minimum and maximum heap size for better performance. For example:
```
export LIBHDFS_OPTS="-Xms64m -Xmx256m"
```
Be careful not to set the minimum to a higher value than the maximum.