Can I back-up my sources?

[Mark Jayson Alvarez]

Hi,
  I only have a 4.9 cd and to upgrade to 4.10 or later
versions, first, I install the sources from my 4.9 cd
and then I use cvsup. Same as with FreeBSD Handbook
and Ports.

Question:

 In upgrading to a higher version of FreeBSD(e.g; 4.9
to 4.10) using cvsup, and I burned the contents of my
upgraded /usr/src to a cd, if my system crashes, will
makeworld work if I copy the contents of the cd into a
fresh /usr/src directory? 

 Same as with FreeBSD Documentation(/usr/doc/en...)
and /usr/ports.

Or does it always have to be done as is?

...because one time, my freebsd crashed and I really
had a hard time fixing it and I end up re-installing
the whole system and running a very long cvsup process
again.

Hope you could help me...

Thanks
-jay

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