I tried to install something via CPAN, but kept getting this error. Even "perl -MCPAN -e 'install CPAN'" gave such error:

Using Tar:/bin/tar xvf /root/.cpan/sources/authors/id/A/AN/ANDK/CPAN-1.9402.tar:
Couldn't untar /root/.cpan/sources/authors/id/A/AN/ANDK/CPAN-1.9402.tar

It wasn't permission, because I was running from root. Maybe the memory. Since this is a OpenVZ container, we would check the /proc/user_beancounters

# cat /proc/user_beancounters

And the output showed two parameters that had "failcnt". To fix, go to the host node, edit /etc/sysconfig/vz-scripts/{CTID}.conf, and change the barrier and limit number for the two parameters, then restart the container.

After the container is restarted, CPAN works fine.