When you untar large tar files even as the root user on your VPS you might run into the error "Cannot change ownership to uid NNN, gid NNN: Disk quota exceeded". This is because the extracted files from the tar archive is being attempted to be created with the original UID and GID as on the system where the tar archive was created. Now if the UID is not already present on the new VPS or if the UID corresponds to a user without a lot of disc quota available the above error will be triggered preventing extraction of the tar.gz archive.