Choose a disk, and save all data from that disk to other disks.
This disk will be the initial Linux system disk.
It will be formatted regardless whatever is on it.
Any (SATA) disk is sufficcient, we need only about 100 Mbytes.
If you happen to have a free disk by accident: fine !
Otherwise it is advised to use the smallest (oldest) disk
you have within reach:
that one is the easiest to free from valuable data.
It is needed only during the process of installing Linux to the BBS2.
Later the system is transferred to the mirrored partitions,
freeing this disk again.
It is not a problem if this disk will be involved
in the mirrored partitions to-be-defined,
since mirrored partitions need not to be complete to function.
It can be added later.
