steveb at aei-potsdam.mpg.de
Sat Apr 13 17:37:42 PDT 2002
This question may be very slightly off-topic, so I apologize.
I'm in the process of setting up a network installation procedure using
PXE/DHCP/NFS/Kickstart w/ RH7.2 for about 150 dual Athlon nodes. These
nodes use a Maxtor 6L080J4 80.0GB HDD and an ASUS A7M266-D motherboard,
among other things. One particular note is that I don't need/want CDROMs
in these systems.
Now, a vendor provided me with a couple of test nodes basically to our
specifications, except that they included CDROMs and floppies. To make a
longish story shorter, I wanted to make sure that the nodes work fine
without the CDROM.
So, I first looked into the BIOS. I disabled (set to "None") Primary
Slave, Secondary Master/Slave (since my HDD is Primary Master), removed
the CDROM from the list of boot devices, and disabled the Secondary IDE
channel. Then, I passed the kernel args "ide0=dma hdb=none" to try to
enforce the HDD to use DMA during the Kickstart installation.
Now, here is the kicker: regardless of the BIOS settings, if I have the
CDROM plugged in (power+IDE, on the secondary channel) the installation
takes ~ 5 times faster than if the thing isn't there. This installation
includes installation of ~470 packages plus formatting the HDD. That's
right, as long as the CDROM is plugged in, everything is peachy, but once
gone, things slow down.
I think this is a problem with the DMA settings, b/c when I pass
"ide=nodma" to the kernel, WITH the CD attached, performance is
slow. However, I can't even force DMA to be used.
If anyone has any suggestions or similar experiences, please let me know.
Thanks a bunch!
Steve Berukoff tel: 49-331-5677233
Albert-Einstein-Institute fax: 49-331-5677298
Am Muehlenberg 1, D14477 Golm, Germany email:steveb at aei.mpg.de
More information about the Beowulf