Netbackup compression

Hi Guys.

I have read a lot about compression.IN NBU admin guides also and in the forums.

SOftware compression is not encouraged.

I know that NBU will backup the compressed files as it is.It does not decompress before backing it up.

Now  on a Windows OS,I have  a compressed folder.:

1.what happen if compresed option is checked in policy? will that folder be decompress first ,then NBU will read the data..is it?

2.if not checked in policy?

Now  on a Windows OS,I have  a  folder.:

3.what happen if compresed option is checked in policy? decompression occurs here before backup?

4.if not checked in policy?

NBU 7.5