On Mar 8, 2012, at 3:12 AM, [email protected] wrote:

> Hi ceph-devel,
> I came up with the following problems when I tried to let Hadoop use Ceph. 
> Could you give any advice? Thanks firstly!
> I installed ceph-0.20.2 and hadoop.0.20.205.0 with the 
> hadoop.0.20.205.0-cephfs1.patch successfully. Both ceph and hadoop(using 
> HDFS) can work well separately. Besides, I could run command like 'hadoop fs 
> -ls /', 'hadoop fs -put /localfilepath /cephfilepath' correctly. But when I 
> run a mapreduce demo: wordcount with a small file containing about two 
> thousand words, reduce task crashed reporting information like: 
> A fatal error has been detected by the Java Runtime 
> Environment:...Problematic frame:C  [libceph.so.1.0.0+0x898e7]…

Hi Xiaobing,

It's a good sign that you are able to use 'hadoop fs -put' to load data into 
Ceph. There are some edge cases with library loading that aren't quite robust 
enough yet. It would be great if you could provide some more information:

1. What distribution are you using?
2. When the crash occurs there should be a large block of text along side the 
"Problematic frame…" message that the JVM dumps out. Could you post that here?
3. The JVM should be producing a file that looks like "hs_err_pid1201.log". 
Attaching that is also helpful.

You are definitely correct that having version mis-matches can cause problems, 
so making sure to have a clean installation is important when you are switching 
versions of Ceph and Hadoop. On the wiki 
http://ceph.newdream.net/wiki/Hadoop_FileSystem there are specific Git SHA1 
versions that are known to work on Ubuntu 11.10.

Thanks,
Noah--
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