I was directed to post this on the mailing list. See the following forum post as a reference. http://www.centos.org/modules/newbb/viewtopic.php?topic_id=16710&forum=42 I formatted my external ext3 372GB USB hard drive in ubuntu and now want to use it in Centos. I made sure that my group/user numbers were the same. I was not able to write to the mounted USB hard drive (HD). I suspected selinux and shut it of and I was able to copy the file! I set selinux back to enforce and rebooted. I like the security features of selinux. I tried: 1) chcon -v 2) restorecon -Rv /media/disk 3) cp -P and still am not able to write to the USB HD. The sad part is I can delete files from the USB HD. See forum post for details. I tried it in fedora 9 and it is able to write to the USB HD I tried an 32GB USB memory stick in Centos 5.2 and it worked! I am wondering why it doesn't work for my USB HD? The only difference is the the size. Your help would be much appreciated.