This could be due to several reasons, but it's probably because the appropriate driver is not configured in the kernel. Check and make sure the appropriate driver (EATA-DMA or EATA ISA/EISA/PCI for most DPT cards) is configured.
The RAID has not been configured properly. If you're using a DPT storage manager, you need to configure the RAID disks as a single logical array. Michael Neuffer ( ) writes: "When you configure the controller with the SM start it with the parameter /FW0 and/or select Solaris as OS. This will cause the array setup to be managed internally by the controller."
As stated in the DPT manual, this is clearly a no-no and might require the disks to be returned to the manufacturer, since the DPT Storage Manager might not be able format it. However, you might be able to perform a low level format on it, using a program supplied by DPT, called clfmt in their utilities page. Read the instructions after unzipping the clfmt.zip file on how to use it (and use it wisely). Once you do the low level format, you might be able to treat the disks like new. Use this program carefully!
When you do a mke2fs on the SCSI drive, you may see errors of the form:
scsi: aborting command due to timeout : pid xxx, scsi0, channel 0, id 2, lun 0 write (10) xx xx xx xx xx xx xx xx xx eata_abort called pid xxx target: 2 lun: 0 reason: 3 Returning: SCSI_ABORT_BUSY
and this might end up causing the machine to freeze. I (and many others) have been able to fix this problem by simply reading one or two hundred MB from the RAID array with dd like this:
% dd if=/dev/sdX of=/dev/null bs=1024k count=128
During a format, a fast rush of requests for chunks of memory that is directly accessible is made, and sometimes the memory manager cannot deliver it on time anymore. The dd is a workaround that will simply create the requests sequentially instead of one huge heap at once like the format tends to create it.
Read the SCSI-HOWTO again. Check the cabling and the termination. Try a different machine if you have access to one. The most common cause of problems with SCSI devices and drivers is because of faulty or misconfigured hardware. Finally, you can post to the various newsgroups or e-mail me, and I'll do my best to get back to you.