Warning to those updating to latest 0.19

[Jean-Daniel Cryans <jd...@apache.org>]

Hi devs,

I just committed HBASE-698 which recovers any log on HDFS when the
Master starts and I'm sure everyone will see the difference. It also
solves the "I killed -9 my local HBase and now everything is gone"
problem, at least if the append took place.

WARNING: Tho this is a nice fix, it will also recover any log
directory in HBase's root folder. To prevent any issues, it is
strongly recommended to first delete those folders (with HBase being
down) before upgrading. I'm thinking about all those setups in
production that runs on 0.19 since some time that may have tons of
those log dirs. Simply issue something like HADOOP_HOME/bin/hadoop dfs
-rmr /HBASE_ROOT/log_*

Thx,

J-D