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)
Juniper Networks EX3300 EX3300-48P 48-Port Gigabit PoE+ Switch
$40.12
Juniper Networks EX2300-C 12-Port 2XSFP Uplinks PoE+ Switch P/N: EX2300-C-12P
$299.99
JUNIPER EX3400-48P 48x 1GB PoE+ RJ-45 4x 10GB SFP+ 2x 40GB QSFP+, DUAL AC POWER
$210.00
Juniper EX4600-40F-AFI 24 SFP+/SFP Ports 4 QSFP+ Ports Dual AC Switch
$999.00
Juniper Networks EX4300-48T 48 Port Gigabit 4 QSFP 40G 2xPSU AFO Network Switch
$89.00
Juniper Networks EX3300-24P | 24 Port Gigabit Network Switch w/ Power cord
$53.99
Juniper EX3400-48P 48-Ports PoE+ 4x SFP+ and 2x QSFP+ Managed Switch Tested
$205.00
Juniper EX3300-48P, 48 Port PoE+ Gigabit Network Switch w/ Power cord
$54.99
Juniper EX2300-48P PoE+ Switch 48x 1GbE & 4 SFP+/SFP 10G uplinks, Tested
$289.00
New Factory Sealed Juniper EX2300-48P Networks 48-Port Managed Ethernet Sealed
$499.00