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 Server Rack Cabinet 9308-RC4
$209.00
IBM System X3250 M3 Server 8GB RAM Intel Xeon x3440 2.53ghz (NO HDD)
$41.99
IBM System p5 9131-52A 3.5" 4-Bay Server 80P6787 1 CPU 2GB 6 HD CADDIES TAPE BU
$250.00
IBM Power S822 8284-22A 12SFF Power8 3.89GHz 6Core 64GB RAM No HDD Server System
$359.99
IBM Power S822 8284-22A 12SFF Power8 3.89GHz 6-Core 64GB RAM No Bezel/HDD Server
$279.99
IBM x3650 M4 Server Intel Xeon E5-2640 (x2) 144GB RAM No HDDs (#4XN7N)
$169.99
COMPLETE IBM 9009 41A ISERIES POWER9 ENTRY LEVEL SERVER FULLY TESTED AND WORKING
$3550.00
IBM System x3550 M3 Dual Intel Xeon X5650 @2.67GHz 32GB RAM No HDD
$68.50
IBM x3550 7042-CR4 Server System Intel Xeon 5130 2.00Ghz DVD-Rom Drive 1GB No HD
$139.99
IBM QRadar xx29 Server 4412Q2A
$209.99