hi:
i want install RHEL AS4 on my server.
i have a server with supermicro motherboard and two scsi HDD and raid controller.
when in wat install RHEL as4,i have not any problem until that the automatically partition page appear.in this page this error message appear:
error mounting file system sda1 invalid argument.
error mounting file system sdb1 invalid argument.
Note:
FC5 is install now on this server now.

cau you help me?

I'm not at all familiar with RHEL or your hardware but if an install fails for no obvious reason it is usually possible to open a shell from the install screen and have a look at the log files (e.g. /var/log/syslog, /var/log/messages). These are in a ramdisk so they disappear when you reboot. If your hardware is really old or really new you might have problems with things like SCSI controllers.

Another way to check out new hardware is with a live CD like knoppix, which will start up even it disks cannot be mounted, and you can investigate further.