I studying user logs on the two node cluster that I have setup and I was wondering if anyone can shed some light on these "attempt*' directories
attempt_201212051224_0021_m_000000_0 attempt_201212051224_0021_m_000003_0 job-acls.xml
I mean its obvious that its talking about 3 attempts for Map task and 1 attempt for reduce task. However my current MR job only results in some output written to "attempt_201212051224_0021_m_000000_0". Nothing is the reduce part (understandably since I don't even have a reducer, so my question is:
1. The two more M attempts. . . what are they?
2. Why was there an attempt to do a Reduce when no reducer was provided.implemented
3. Why my master node only had 1 attempt for M task but the slave had all that's displayed and questioned above (the 'ls' output above is from the slave node)