do we have an easy way of loading the some of the name nodes (and
data nodes) local directories into HDFs space? This is an easy trick
that would make it trivial to apply map-reduce to distributed log
grepping. Should we add that? Had good success with this sort of
thing with previous systems.
EG.
hdfs://blah:6666/SYSTEM/namenodes/<host:port>/logs/
just points allows one to HDFS browse the logs directory of a name
node. Can then use the plan-9 trick of putting all kinds of API info
into "files" on the data nodes (be they real files or CGI equivalents).
Should I file a bug on this?
On Mar 30, 2006, at 4:08 PM, Yoram Arnon (JIRA) wrote:
[ http://issues.apache.org/jira/browse/HADOOP-96?page=all ]
Yoram Arnon reassigned HADOOP-96:
---------------------------------
Assign To: Hairong Kuang
name server should log decisions that affect data: block creation,
removal, replication
---------------------------------------------------------------------
------------------
Key: HADOOP-96
URL: http://issues.apache.org/jira/browse/HADOOP-96
Project: Hadoop
Type: Improvement
Components: dfs
Versions: 0.1
Reporter: Yoram Arnon
Assignee: Hairong Kuang
Priority: Critical
currently, there's no way to analyze and debug DFS errors where
blocks disapear.
name server should log its decisions that affect data, including
block creation, removal, replication:
- block <b> created, assigned to datanodes A, B, ...
- datanode A dead, block <b> underreplicated(1), replicating to
datanode C
- datanode B dead, block <b> underreplicated(2), replicating to
datanode D
- datanode A alive, block <b> overreplicated, removing from
datanode D
- block <removed> from datanodes C, D, ...
that will enable me to track down, two weeks later, a block that's
missing from a file, and to debug the name server.
extra credit:
- rotate log file, as it might grow large
- make this behaviour optional/configurable
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