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From "Doug Cutting (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-158) dfs should allocate a random blockid range to a file, then assign ids sequentially to blocks in the file
Date Tue, 30 May 2006 20:33:30 GMT
    [ 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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