why not store the cluster in the data node?
On May 17, 2006, at 6:39 PM, Konstantin Shvachko (JIRA) wrote:
[ http://issues.apache.org/jira/browse/HADOOP-124?
page=comments#action_12412273 ]
Konstantin Shvachko commented on HADOOP-124:
--------------------------------------------
For future development in this direction.
We should persistently store on the name node all storage IDs,
which the
name node ever assigned any blocks to.
With that knowledge the name node can reject blocks from any newly
registered data storages that are not on the name node list.
In other words when a data node registers NEW data storage it
should not
report any blocks from that storage, and the name node can
effectively verify
that since it never assigned any blocks to this storage.
This would prevent us from accidentally connecting data nodes
representing
different clusters (DFS instances).
don't permit two datanodes to run from same dfs.data.dir
--------------------------------------------------------
Key: HADOOP-124
URL: http://issues.apache.org/jira/browse/HADOOP-124
Project: Hadoop
Type: Bug
Components: dfs
Versions: 0.2
Environment: ~30 node cluster
Reporter: Bryan Pendleton
Assignee: Konstantin Shvachko
Priority: Critical
Fix For: 0.3
Attachments: DatanodeRegister.txt, DirNotSharing.patch
DFS files are still rotting.
I suspect that there's a problem with block accounting/detecting
identical hosts in the namenode. I have 30 physical nodes, with
various numbers of local disks, meaning that my current 'bin/
hadoop dfs -report" shows 80 nodes after a full restart. However,
when I discovered the problem (which resulted in losing about
500gb worth of temporary data because of missing blocks in some of
the larger chunks) -report showed 96 nodes. I suspect somehow
there were extra datanodes running against the same paths, and
that the namenode was counting those as replicated instances,
which then showed up over-replicated, and one of them was told to
delete its local block, leading to the block actually getting lost.
I will debug it more the next time the situation arises. This is
at least the 5th time I've had a large amount of file data "rot"
in DFS since January.
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