PE2650 RH7.3 and CD-ROM DMA

Darrin Hyrup shades at
Mon Jun 24 16:18:01 CDT 2002


I have a weird problem on one of my new servers...  It is a brand new dual 
processor 2.0GHz PE2650 with 2GB RAM, 4x18GB U160M drives configured for 
RAID5 on the internal PERC3/Di, and has the standard Dell 24X [Samsung 
SN-124] internal CD-ROM.

I just loaded a fresh install of Red Hat Linux 7.3 onto the server and 
updated to the latest errata kernel (2.4.18-5smp).  The installation went 
fine and the system itself runs without incident, however when I mount the 
CD-ROM drive and try to copy over some RPM files off my installation disks, 
the whole machine locks up soon as the copy starts.  I can browse the 
CD-ROM filesystem fine, the problem only happens when I actually try to 
copy a file.  I rebooted and tried again to make sure it wasn't a fluke, 
and the second time I did it, there was a short on-screen message stating 
that OSB4 was in an impossible state and that I may need to adjust my DMA 

I don't think I can adjust the DMA on the RAID array (and I don't think 
that I'd want to), but the CD-ROM does show as using DMA according to 
"hdparm -i /dev/cdrom".

Disabling the DMA via "hdparm -d0 /dev/cdrom" appears to work, however, 
should I need to do that?  I know that most of these machines are tested by 
Dell with the latest OS and kernel releases, so I would assume this 
configuration would run out of the box.

If I do need to keep using hdparm, should I use the -k setting as well in 
my startup script?



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