well, damn I was hoping that was my issue but I guess it's something else. I have mounted some network drives via fstab with the following lines:
//128.251.108.xxx/Data/Agilent_Data /home/lv_admin/uslonsnas001 cifs cred=/etc/.na02passwd,rw,umask=0000,uid=www-data,gid=webgroup 0 0
//128.251.108.xxx/c$/Agilent /home/lv_admin/uslonsapp003 cifs cred=/etc/.na02passwd,rw,umask=0000,uid=www-data,gid=webgroup 0 0
but can't use the php command mkdir() on either of those drives....