This message comes from tar and not from perl.

If you wish to keep the root "/" then have a look at the -P switch in the tar manpage:

    tar -Pcz /usr/fweb/xyz/abc > /usr/fweb/xyz/aa.tar.gz

    or 

    tar -Pczf /usr/fweb/xyz/aa.tar.gz /usr/fweb/xyz/abc
[download]

--
John.