At 11:11 PM +0100 2000/2/23, Brad Knowles wrote:
> I have switched to a non-SMP kernel (otherwise identical to what
> I was previously running), I have tried moving both of the 2940U2W
> controllers to either the primary or secondary PCI busses (on the
> primary, one of them shared IRQs with the AIC-7890 controller, but
> on the secondary although they share the PCI bus with the AIC-7890
> controller they all at least have different IRQs and I/O Base
> Addresses). So far, nothing has worked.
After working with the experts from Germany and the local field
engineers, it appears that the problem was within the drive array
configuration. It has two controllers (with one UltraSCSI 2 LVD
interface each), and the two logical units on the array are
accessible via both of them and visible to the host as two different
devices.
Although I was mounting only one each of the two logical units,
it appears that control over these LUs was ping-ponging back and
forth between the two controllers, thus trashing my throughput.
Now that the problem has been fixed, initial preliminary test
results indicate that I do actually see almost 2x speedup using two
host SCSI controllers to the two different drive array controllers.
I'm now moving one of the host SCSI adaptors back to the other PCI
bus, to see if that helps, hurts, or makes no difference to the
performance.
If it doesn't hurt, I plan on leaving them on separate PCI busses.
Afterwards, we're going to delete and recreate the logical units
on the controller, so that we have a separate device for each column
of disks (half of which will be made available through each
controller), and then we're going to try software striping across the
columns.
This ought to be fun! ;-)
--
These are my opinions and should not be taken as official Skynet policy
_________________________________________________________________________
|o| Brad Knowles, <[EMAIL PROTECTED]> Belgacom Skynet NV/SA |o|
|o| Systems Architect, Mail/News/FTP/Proxy Admin Rue Col. Bourg, 124 |o|
|o| Phone/Fax: +32-2-706.13.11/726.93.11 B-1140 Brussels |o|
|o| http://www.skynet.be Belgium |o|
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