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Posted to common-user@hadoop.apache.org by Michaela Buergle <Mi...@neofonie.de> on 2008/04/10 16:54:21 UTC

Formatting the file system: Misleading hint in Wiki?

Hi all,
on http://wiki.apache.org/hadoop/GettingStartedWithHadoop - it says:
"Do not format a running Hadoop filesystem, this will cause all your
data to be erased."

It seems to me however that currently you better not format a Hadoop
filesystem at all (after the first time, that is), running or not because:

"Now if the cluster starts with the reformatted name-node, and not
reformatted data-nodes the data-nodes will fail with
java.io.IOException: Incompatible namespaceIDs ..."
(http://issues.apache.org/jira/browse/HADOOP-1212 + personal experience)

If I haven't missed an obvious solution to this problem, I suggest
mentioning that issue in the Wiki.

micha

Re: Formatting the file system: Misleading hint in Wiki?

Posted by Colin Freas <co...@gmail.com>.

This has been my experience as well.  This should be mentioned in the
Getting Started pages until resolved.

-colin



On Thu, Apr 10, 2008 at 10:54 AM, Michaela Buergle <
Michaela.Buergle@neofonie.de> wrote:

> Hi all,
> on http://wiki.apache.org/hadoop/GettingStartedWithHadoop - it says:
> "Do not format a running Hadoop filesystem, this will cause all your
> data to be erased."
>
> It seems to me however that currently you better not format a Hadoop
> filesystem at all (after the first time, that is), running or not because:
>
> "Now if the cluster starts with the reformatted name-node, and not
> reformatted data-nodes the data-nodes will fail with
> java.io.IOException: Incompatible namespaceIDs ..."
> (http://issues.apache.org/jira/browse/HADOOP-1212 + personal experience)
>
> If I haven't missed an obvious solution to this problem, I suggest
> mentioning that issue in the Wiki.
>
> micha
>