Hi,
we discussed the three kinds of data looses, hardware, software or
human errors.
I would love to figure out what was my problem today. :)
Scenario:
+ updated from hadoop .2.1 to .4.
+ problems to get all datanodes started
+ downgrade to hadoop .3.1
+ error message of incompatible dfs (I guess . already had started to
write to the log)
All transaction done with .2 during last hours lost. Means the data I
created and copy was not in the dfs any more.
I guess the update / downgrade process destroyed the log but the
image itself was still ok.
I ended up with a complete corrupted dfs - I guess since the lost dfs
namenode transaction log.
Wouldn't be better in case we discover a version conflict in the dfs,
that the user need to do manually confirm that the data have to
converted into a new format.
Any thoughts?
Thanks.
Stefan
