How setup copied partition to boot properly?

[giovanni_re]

What modifications are necessary to a (K)Ubntu 904 partition, to make it properly bootable when copied to a different partition?

==  BACKGROUND:   sda5 -> sda7
I have a KU 904 install that boots fine. Preparing to do a 910 install & upgrade, I copied the 904 partition from sda5 to sda7 (sda6 is the swap).  I then did a 910 install on sda8.  The install properly found the 904 linux kernels on sda5 & sda7, & added them to the grub boot menu, stored on the MBR.  Both the 910 on sda8 & the 904 on sda5 boot properly.

==  PROBLEM:  BOOTING SDA7 USES SDA5 AS / (ROOT)
When I boot, & select sda7 from the GRUB boot menu, trying to boot into the sda7 904 copy from sda5, the system boots fine, but the 'mount' command shows that it is sda5, not 7, that is mounted as root.  Further, it is also using info from my home directory on sda5 (not sda7, as it should).

I'm guessing that during boot up, either
a) it starts booting from sda7, but then from sda7 finds some info that tells it to mount sda5 as root, or,
b) less likely I suspect: Although GRUB shows the linux kernel on sda7 as an option (which I select), it is somehow actually booting from sda5, not 7.

==  SOLUTION?  How boot from copied partition sda5 -> sda7?
So, I'm guessing option 'a' above is what is happening.  If so, what changes (directories, files, values) do I need to change on sda7, so that the boot up sequence will properly boot off sda7, & mount sda7 as "/" (root), & use the files from /home on sda7?


Thanks :)