We have a NFS server provide home directory for many account, which provided by a NIS server. I have account A and B. In /home/A, I try to copy "cp -a /home/B/somedir ~/". Then I found in /home/A/somedir, all files are owned by user A. Then if I do "chown -R B:B somedir", I got "Operation not permitted" error. I am user A, "cp -a" didn't preserve the original user (B). Then I cannot chown my own files. Any suggestion? I fix my own issue by "chmod 777 /home/A", "su - B" and "cp -a somedir /home/A/", and "su - A", then "chmod 755 /home/A". But it is not a good solution.