possible bus loading problem during resync

["Timothy D. Lenz" <tlenz@vorgon.com>]

I'm working on 2 systems that are mainly for running vdr. I've had these 
running somewhat for awhile with raid. But a couple nights ago as I was 
quitting for the night, I noticed one of the computers drive light 
staying on. I had just made some changes to xine and didn't know if 
something had crashed. Turned on the TV and found the video was freezing 
for 10-20secs every 10-20secs. Logging in using putty and winscp I found 
it very sluggish to respond.Starting top I found it was doing the 
regular array check/resync. The process was using about 64% cpu and cpu 
was staying at idle speed (1000Mhz). These computers use Athlon64 x2 
cpu's. A problem with the AN2 socket systems is that when the cpu is 
throttled back, it also slows the bus. This has been found to be a 
problem on boards with integrated graphics when using nvidia's vdpau for 
hardware video decoding because they use system ram. The fix is to set 
the lower speed limit to 1800Mhz and/or change the up_threshold to ~50% 
. However, I am using PCIe video cards and so up till now have not had a 
problem.

I stopped vdr, but putty and winscp where still sluggish. This tells me 
that it is loading the bus so much that both the video card and the 
network is effected. it would also effect any tuner cards interfering 
with any recording that may be going on at the time. I change the 
up_threshold from the default 95% to 50% which should kick the speed up 
when it's syncing. But I'm not sure that will be enough. Could there be 
some other setting that is wrong raising the priority of the process? 
Seems like this would be a problem for any system having raid 
maintenance bring the system to its knees. The eta to finish was 75 minutes.