Home | About | Sematext search-lucene.com search-hadoop.com
 Search Hadoop and all its subprojects:

Switch to Threaded View
HBase, mail # user - ExportSnapshot very slow. bug?


Copy link to this message
-
Re: ExportSnapshot very slow. bug?
Matteo Bertozzi 2013-11-08, 19:06
The first copy doesn't resolve the links, so you're copying empty files.
The data copy is only on "step 2" with the MR job

Matteo

On Fri, Nov 8, 2013 at 10:54 AM, Bryan Beaudreault <[EMAIL PROTECTED]
> wrote:

> Hello all.  I'm trying out the ExportSnapshot tool and it is extremely
> slow.  I took a look at the code and I think I know why.
>
>
> https://github.com/cloudera/hbase/blob/cdh4-0.94.6_4.4.0/src/main/java/org/apache/hadoop/hbase/snapshot/ExportSnapshot.java#L635
>
> In step 1 it is for some reason copying from fs1 to fs2.  This basically
> means in a single threaded process we are copying an entire hbase table to
> another cluster.  I can understand wanting to copy from fs1 to fs1 (i.e.
> different path on same fs), so as to dereference all the soft links of the
> snapshots.  But why between filesystems?
>
> In step 2 you finally do the MR job, which makes much more sense, but as
> far as I can tell all of the files would already exist, as FileUtils.copy
> just does a recursive copy of all paths in a tree.
>
> Am I missing something?  I appreciate any input.
>
> - Bryan
>