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http://issues.apache.org/jira/browse/HADOOP-158?page=comments#action_12413893 ] 

Doug Cutting commented on HADOOP-158:
-------------------------------------

Why must the file-id part of the block id be random?  Can't that be sequential?

> dfs should allocate a random blockid range to a file, then assign ids 
> sequentially to blocks in the file
> --------------------------------------------------------------------------------------------------------
>
>          Key: HADOOP-158
>          URL: http://issues.apache.org/jira/browse/HADOOP-158
>      Project: Hadoop
>         Type: Bug

>   Components: dfs
>     Versions: 0.1.0
>     Reporter: Doug Cutting
>     Assignee: Konstantin Shvachko
>      Fix For: 0.4

>
> A random number generator is used to allocate block ids in dfs.  Sometimes a 
> block id is allocated that is already used in the filesystem, which causes 
> filesystem corruption.
> A short-term fix for this is to simply check when allocating block ids 
> whether any file is already using the newly allocated id, and, if it is, 
> generate another one.  There can still be collisions in some rare conditions, 
> but these are harder to fix and will wait, since this simple fix will handle 
> the vast majority of collisions.

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