ISE 6.1 installer on a Linux machine does misinterpret Free space on a disk and occupied space!
The "available" field shows a percentage which looks like it is detecting the space used.
Your disk space available is less thhan the disk space required. The
information will be terminated.
This has not been reproducable. Please check the following and contact Roy White if you see one of these cases.
install to another drive and see the same behavior?
to install to a network drive and copy it back to his local drive.
copy enough stuff onto the drive, and then the installer will let it continue and he could delete the junk files off the
drive after install completes.