This message occurring during boot up of KNOPPIX-Live has no deleterious consequences but it is an annoyance.
It is probably an unintended hangover from the HD-installed version which allocates several partitions.
Either ignore it or include a (2nd and) 3rd (and 4th) partition in your boot device, even if it is a USB stick.
Use fdisk* to set /dev/{sda}1 as the KNOPPIX partition type c (being FAT32; or NTFS if you prefer - I've never tried this).
Set /dev/{sda}3 as type 83 (Linux) (at least 400M). Then format it as Reiserfs with mkreiserfs .
It's not obvious to me how (or even whether) the partition is used; but it is made available; and you will boot
without the annoying error message!
(*) Yes: you need to format your intended USB device - from a temporary KNOPPIX USB device is probably your most
convenient method ;o)
IBM System X3650 Server M2 2 x Xeon X5570 2.93 Ghz w/128 GB/DVDRW
$169.99
IBM Power S822 12-Bay Server System Power8 Core 3.42Ghz DVD-Rom Drive 64GB No HD
$399.99
IBM SYSTEM x3200 M2 Server - HDD wiped, No OS
$75.00
IBM Power 720 POWER7 00E6516 3.6GHz CPU 64GB RAM Server
$209.98
$16000.00
IBM 7944AC1 System x3550 M3 Server 1*Intel Xeon X5650 2.67GHz 4GB SEE NOTES
$27.25
IBM Lenovo X3650 M5 2U 8x 2.5” CTO Rack Server – 2x HS, 2x 750W
$199.00
IBM Power S822 8284-22A 12SFF Power8 3.89GHz 6-Core 64GB RAM No Bezel/HDD Server
$319.99
IBM 8203 E4A p520 Server 8203-E4A 4.2GHz 2-Core POWER6 32GB RAM / NO HDD USED
$99.99
IBM Intel EXPI9404PTL Pro/1000 PT Quad Port Server Adapter PCI-E 39Y6138 Free SH
$16.99