Groupping restored partitions into slices

[Snow Mountains]

Thomas, thank you great info (didn't know for GPT). However, I
successfully restored my slices.

I post this method here for someone with similar problem in the future:

* deleted first 2k of data from ad4 using dd if=/dev/zero of=/dev/ad4 count=2

* created fdisk configuration file with three slices; I determined the
size by simply calculating the sum of slice sizes as reported by
scan_ffs;

* then /dev/ad4s1-3 appeared;

* then used scan_ffs on each new slice and used these results to
create three new bsdlabels;

* used gpart info to activate swap partitions in bsdlabel file;

* write you this mail from restored system.

Thank you for all the info.
SergiM