Mahadev Konar wrote:
Hi Luca,
Can you do a ls -l on /mapredsystem and send the output? According to
permissions for mapreduce the system directories created by jobtracker
should be world writable so permissions should have worked as it is for
hod.
No, it doesn't appear to be working that way. The mapred system
directory specified by HOD for a jobtracker is /mapredsystem/<hostname>.
When the job tracker starts, it creates this directory with permissions
rwx-wx-wx. It does not clean it up when it stops. But when it is started
again on the same node, I think (may be wrong here) it tries to clean up
the directory (possibly to handle crashes etc ?). This seems equivalent
to issuing a "hadoop dfs -rmr /mapredsystem/<hostname>"which in turn rm
-r of unix. So, it basically has to read the directory to recursively
delete; and because there are no read permissions, it fails.
A simple experiment to simulate the same set of DFS operations using 2
different users, without using mapred, give the same result. Enabling
read permissions allows the delete to work.
There appear several ways we can fix this, and that discussion should go
on HADOOP-2899. Will post my comments there.
Thanks
hemanth
