[gPXE] Booting MS-DOS using gPXE/iSCSI: C: drive is read only

[ACS]

I just managed to setup my diskless DOS boot using gPXE and iSCSI
DOS (6.22) boots OK, even old games (ancient doom) that are present in the 
DOS disk image start fine.
However, I can't write anything to c:\ !
executing:
echo 1 > c:\test.txt
results in general failure error, and a 0 bytes file on disk


dnsmasq/ietd on centos 5.3.
used  iSCSI target is writable when connected from XP/Windows7
Used rom-0-matic to download stable ISO image, for RTL8139


Any hints welcome.....