By default, the vxassist make command creates a concatenated volume that uses one or more sections of disk space. On a fragmented disk, this allows you to put together a volume larger than any individual section of free disk space available.
If there is not enough space on a single disk, vxassist creates a spanned volume. A spanned volume is a concatenated volume with sections of disk space spread across more than one disk. A spanned volume can be larger than any disk on a system, since it takes space from more than one disk.
# vxassist [-b] [-g diskgroup] make volume length
# vxassist -b make voldefault 10g