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)
Everex disk drives for parts vintage NOT TESTED
$39.99
Vintage NEC MultiSpin 3XP External SCSI CD-ROM CDR-400 083A UNTESTED
$44.99
Vintage Apple Computer Employee Macintosh IIfx 2.5" Button Pin "Wicked Fast"
$49.00
NMB KEYBOARD RT2258TW NMB PS/2 BEIGE 121944-101 REV A VINTAGE NEW OLD STOCK
$25.99
Vintage Apple MacWorld Magazine Mousepad
$15.00
Vintage 1990 Apple Data Modem 2400 Box-A/C Adapter-Manual-G5432- READ s8
$144.99
Vintage RARE Apple PC 5.25 Drive A9M0110 for Macintosh-NEW Open Box b2
$399.99
VINTAGE APPLE MACINTOSH M0110 KEYBOARD 128K 512K PLUS WITH ORIGINAL CABLE
$199.99
Vintage Rare Apple Macintosh SE 30 Model M5119 1988 Computer Powers On Needs IOS
$99.00