hadoop-common-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "eric baldeschwieler (JIRA)" <j...@apache.org>
Subject [jira] Created: (HADOOP-1292) dfs -copyToLocal should guarantee file is complete
Date Tue, 24 Apr 2007 17:27:15 GMT
dfs -copyToLocal should guarantee file is complete

                 Key: HADOOP-1292
                 URL: https://issues.apache.org/jira/browse/HADOOP-1292
             Project: Hadoop
          Issue Type: Improvement
          Components: dfs
            Reporter: eric baldeschwieler

We should copy to a temporary file, maybe _tmp.<realname>, and then rename the file
when the copy is complete.  Restarting a copy should reuse the _tmp file, just checksumming
it.  Then ^Cing a copy will do the right thing.

Original suggestion:

On Apr 23, 2007, at 2:38 AM, Richard Kasperski wrote:

I'd like to have a guarantee that a file copy is both completed and that the file is whole.
In the past I've done this  by copying the file to a temporary name tmp.<realname> and
then moving it to <realname> once I have the file copy is complete. This has the following
very nice properties; If the <realname> exists then the file copy is complete and I'm
not looking at a partial copy of the file. I believe that the copy to the cluster has both
of these properties in that the file doesn't appear in a DFS directory until the whole file
has been copied. The copy from the cluster to a local file system does not have these guarantees
and it would be very nice if it did. There are two scenarios under what I wish to use this.
First is that if I ctrl-c the 'hadoop dfs -copyToLocal' I know what parts are complete and
what parts aren't. Second I can run a background compressor to compress the files as they
are copied.

This message is automatically generated by JIRA.
You can reply to this email to add a comment to the issue online.

View raw message