Re: Poor RAID5 performance on new SMP system

[Richard Scobie <richard@sauce.co.nz>]

Marc Marais wrote:
> I've moved one of the IDE cards to the 64 bit bus and thats improved things a
> lot. The 2nd card isnt 3.3v capable and won't go into the 64 bit slot though
> so I'm going to replace it. 
> 
> I noticed using vmstat that the average latency (await) is over 50ms for the
> card on the secondary PCI bus and less than 20ms on the 64 bit bus... Very
> interesting...

Glad it's not going to be a total loss.

I find AMD's behaviour over this bug to be very disappointing - 
motherboards using this broken south bridge can still be purchased today 
and the box does not state "Secondary PCI bus throughput limited to +- 
25MB/s". You will not find this problem mentioned on their website either.

The board I tested is only 9 months old and when I pulled the SCSI card 
and discs and placed them on the 33MHz bus of an equivalent dual Xeon 
board, the throughput went up to +-90MB/s.

I was a big AMD fan prior to this, as the bang for the buck is way 
better, but the time, money and effort wasted left a bad taste.

Regards,

Richard