Append files in Hadoop?

Can I really append a file in HDFS OR do i need to always replace the file? http://hadoop4mapreduce.blogspot.com/2012/08/two-methods-to-append-content-to-file.html

Compression in Hadoop

I am currently researching various options to do compression in Hadoop and found the following articles useful:

• http://comphadoop.weebly.com/index.html
  
• Slide share = http://www.slideshare.net/Hadoop_Summit/kamat-singh-june27425pmroom210cv2
  
• Splitable LZO = http://blog.cloudera.com/blog/2009/11/hadoop-at-twitter-part-1-splittable-lzo-compression/
  

My project needs are = should have minimum performance impact + should give decent compression gains. It looks like my choice is splitable LZO.